Body Hair, Nails, and Wrinkled Fingers

Summary

The parent article, Arguments from Bad Design, asks three questions of any complaint: what exactly is alleged, what task the part performs, and what it costs. This article runs that test on three small features of the human skin.

What is alleged. Charles Darwin wrote in 1871 that the scattered hairs on the human body "are the rudiments of the uniform hairy coat of the lower animals."¹ Robert Wiedersheim in 1895 called the little-finger nail claw-like and a small structure under the nail "the last vestige" of an ape's.² Nobody found calls nails useless. Finger wrinkling is called a "byproduct," not a vestige.³ So the charge is mainly "no present use," which measurement can answer.
Body hair has measured uses. Humans have about as many hair follicles as chimpanzees; the hairs are miniaturized, not missing.⁴ In 29 volunteers, bed bugs on an unshaved forearm were noticed more often than on a shaved one.⁵ Scalp hair on a heated manikin cut the sun's heat reaching the scalp.⁶ Shaving body hair blunts people's ability to feel strong electric fields,⁷⁸ a capacity with no known purpose. The claim that armpit hair spreads pheromones is unproven, because no human pheromone has been shown to exist.⁹
Follicles help heal skin. In mice, stem cells from the follicle rush into a wound,¹⁰ and skin without follicles heals after a delay.¹¹ In a trial on 12 patients, leg ulcers grafted with hair-bearing skin shrank 75% in 18 weeks against 33% for hairless grafts.¹² But in human forearm skin, sweat glands outnumber follicles 2.8 to 1 and do most of this work.¹³
Nails are a sense organ and a tool. People can feel and locate touches on the nail almost as well as on the fingertip.¹⁴¹⁵ Softening the thumbnail with water spoils the sensing of strong fingertip forces.¹⁶ Nails also show disease, from clubbing to Beau's lines,¹⁷ but a diagnostic use is not a design purpose.
Wrinkling needs nerves; its purpose is unsettled. Denervated fingers stay smooth in the bath.¹⁸ Mark Changizi proposed in 2011 that wrinkles work like "rain treads."¹⁹ Kyriacos Kareklas and colleagues found in 2013 that wrinkled fingers moved wet objects in 12% less time.²⁰ Julia Haseleu and colleagues could not reproduce that in 2014.³ Nick Davis found in 2021, with 516 people, that wrinkled fingers grip wet objects as efficiently as dry ones.²¹ A 2015 friction study exists, but its abstract reports no result.²² The score is two for, one against, and every study has a weakness. No later grip study was found.
The creationist replies list functions correctly but overstate twice. David Menton says human hair density matches "most primates";²³ it matches chimpanzees and is far below macaques. Answers in Genesis called wrinkling's use "proven" after one study,²⁴ and the page was never updated after the failed replication.

Verdict: body hair, follicles and nails are shown to have uses. Wet-grip wrinkling is probably real and small, not proven. None of the three settles design against descent, because both views predict a working part with an ancestry-shaped distribution.

Part 1: What exactly is alleged

The parent article separates five charges that travel under the name bad design: poor performance, inherited architecture, damage, tradeoff, and harm.²⁵ The charge against these three features is the weakest kind, the claim that a part does nothing now.

Body hair. Darwin's 1871 statement is the classic one. "Man differs conspicuously from all the other Primates in being almost naked," he wrote, and the remaining "short straggling hairs" are "the rudiments of the uniform hairy coat of the lower animals."¹ He thought the coat was lost "for ornamental purposes," by sexual selection, because hot-country apes keep theirs.¹ Wiedersheim's 1895 catalogue of human vestiges opened with hair: "Man is the least hairy of all the Primates."² Peter Wheeler's 1984 paper in the Journal of Human Evolution is titled "The evolution of bipedality and loss of functional body hair in hominids."²⁶ Isabelle Dean and Michael Siva-Jothy summed up the view in 2012: human fine body hair "is frequently described as non-functional."⁵ Keith Blanchard, writing for The Week in 2014, made underarm hair a charge of poor design: "Hair under your arms? If your body was designed for its current usage, there's a lot of inefficiency there."²⁷

Nails. Wiedersheim wrote that the nails of the fourth and fifth fingers "most nearly suggest the claws of the lower animals," and that a ridge under the free edge is "the last vestige" of a thicker pad in apes.² That is an ancestry claim about a detail, not a claim that nails are useless. Jerry Coyne uses nails the same way, as a trait humans share with "monkeys, apes, and lemurs."²⁸ No source was found that calls human nails functionless.

Wrinkled fingers. No one calls these a vestige. The older view was that they are "an accidental side effect of wetness," the skin simply soaking up water, as Changizi put it when he set out to refute that view.¹⁹ The modern skeptical position is Haseleu's: wrinkling "does not serve any adaptive function but rather is a byproduct" of nerve-driven narrowing of blood vessels.³

So two questions need separating, as the parent insists. Does the part do useful work now? And does its distribution reflect ancestry? A measured use answers the first. It leaves the second untouched.

Part 2: Body hair

Fewer visible hairs, not fewer follicles

The Goosebumps article covers the follicle counts in detail. The short version is Yana Kamberov's 2018 comparison of humans, chimpanzees and macaques: the absence of a visible coat "does not result from a loss of hair follicles per se," but from a shift to "the microscopic, unpigmented vellus hair type."⁴ Human follicle density equals the chimpanzee's. Both are well below the macaque's. The human body is covered in hair. Most of it is too fine and pale to see.

That changes what "vestigial" could mean here. The follicles are all present. What is reduced is the hair shaft each one makes. Any function that depends on the follicle, rather than on a thick coat, is untouched by the reduction.

Measured functions, and how strong each is

Proposed use	Evidence	Strength
Detecting crawling parasites	Dean and Siva-Jothy 2012: 29 students, one forearm shaved, bed bugs released on each	Measured once, small sample
Touch	Follicles carry nerve endings; the parasite study measured detection directly	Measured (same study)
Shading the scalp from sun	Lasisi and colleagues 2023: heated manikin with human-hair wigs	Measured, manikin only
Letting sweat evaporate by staying sparse	Same manikin study shows hair reduces maximal evaporation from the scalp	Measured for scalp hair only
Sensing electric fields	Chapman and colleagues 2005, 16 people; Jankowiak and colleagues 2026, 30 people shaved	Measured; no known purpose
Spreading pheromones from armpit hair	No human pheromone identified	Unsupported
Wicking sweat, reducing armpit friction	Proposed, not tested	Untested

Parasites. Dean and Siva-Jothy shaved one forearm of each of 29 Sheffield students and released marked bed bugs on both arms, a week apart.⁵ "Host 'detections' were more frequent on unshaved when compared with shaved arms" in both men and women.⁵ In men the bugs also searched longer before biting on the hairy arm; in women that difference was not significant. The authors could not separate fine vellus hair from coarser terminal hair, so hairier men may drive part of the result.⁵ No replication was found.

Sun and heat. Tina Lasisi and colleagues mounted wigs on a thermal manikin. They found "a significant reduction in solar radiation influx to the scalp in the presence of hair," and that "maximal evaporative heat loss potential from the scalp is reduced by the presence of hair."⁶ So a dense coat has a real cooling cost, which is the reasoning Menton and Mitchell give for why a sweating animal should not be furred. But the experiment tested scalp hair on a manikin, not body hair on people.

Pheromones. The claim that armpit hair traps and spreads sexual scent assumes human pheromones. Tristram Wyatt's 2015 review found "no robust bioassay-led evidence" that any of the four steroids usually named are human pheromones.⁹ The claim may be right, but it has nothing to stand on yet. The other two armpit ideas, which Vincent Torley listed in reply to Blanchard, are that the hair may "aid the wicking of sweat away from the skin" or "reduce friction between the thorax and upper arm."²⁹ No test of either was found.

Electric fields. C. Elaine Chapman and colleagues exposed the forearm and hand of 16 people to strong alternating fields in 2005. Nine could feel them, and "Subjects were unable to detect AC electric fields when the hair was removed from the forearm and hand."⁷ Kathrin Jankowiak and colleagues tested 30 people in 2026, before and after they shaved head, arms and beard. Thresholds rose significantly for steady and mixed fields, "but not for AC."⁸ Their abstract says hair removal raised thresholds "for all EF types,"⁸ which overstates their own statistics, and the shaved session always came second. So hair is the sensor. The field strengths involved are thousands of volts per meter, the kind people feel under high-voltage power lines.⁸ No study was found that asks whether the ability does anyone any good. It is best read as a side effect of hair's role in touch.

Part 3: Hair follicles and healing skin

A hair follicle is a pocket of skin cells reaching deep into the dermis. When the surface is scraped away, the follicle's lining is still there.

George Cotsarelis's group killed the follicle stem cells in mice in 2005. The skin survived, so those cells are not the daily source of new skin. "After epidermal injury, however, cells from the bulge are recruited into the epidermis and migrate in a linear manner toward the center of the wound."¹⁰ About 26% of the new surface cells at day 8 came from the follicle.³⁰ Abigail Langton and colleagues then wounded mouse tail skin that grows no follicles at all. It healed "with an acute delay," then caught up.¹¹ The reviewers' summary: follicle cells "accelerate the onset of wound healing but are not necessary for wound healing."³⁰

Humans are different, and the difference cuts both ways. Laure Rittié and colleagues made shallow laser wounds on the forearms of volunteers and followed the repair in biopsies. They counted 115 sweat glands and 42 follicle units per square centimeter,¹³ and found that new skin grew out of both at the same rate.¹³ They also noted that hairless palms and soles "have no inherent healing defects."¹³ On this count follicles supply roughly a quarter of the appendage-based repair in forearm skin.³¹

A clinical trial shows that follicles still matter in people. María-Luisa Martínez and colleagues grafted hair-bearing scalp skin into one half of each patient's leg ulcer and hairless skin into the other half. After 18 weeks the follicle halves had shrunk 75% against 33%, in only 12 patients.¹²

Scars show the cost of losing them. "Typically, wound healing in adult mammals results in scar tissue that lack skin appendages."³⁰ A scar has no follicles and no sweat glands, and it is weaker and less sensitive than the skin it replaced.

Part 4: Nails

What nails do

A touch surface. Benjamin Seah and colleagues tested 300 fingers in 30 people. Moving two-point discrimination was 2.4 mm on the nail and 2.2 mm on the pad, which they judged clinically equal. Static discrimination and light-touch thresholds were better on the pad.¹⁴ Matthew Longo found in 2024 that people locate touches on the nail with a precision "not appreciably lower than that of the fingertips."¹⁵

A stiff backing. The traditional view is that the nail gives the pad something hard to press against.¹⁵ Trevor Brothers and Mark Hollins tested one version of this in 2014. They soaked the thumbnail to soften it, and force matching got worse at 1,000 grams while staying normal at 100 grams.¹⁶ Their reading is that nerve endings under the nail sense strong forces through a rigid plate.

Picking things up. Rikiya Shirato and colleagues timed 38 volunteers on a standard hand test with nails cut to 0 mm, and again 20 days later with 2 mm of nail. Three of the ten tasks were significantly faster with nail: a medium sphere, a small cube and a pin.³² But every subject did the 0 mm test first, so practice could explain some of the gain.

Protection and scratching. The skin under the free edge seals the nail bed; Christian Dumontier calls it "the first barrier of defense preventing bacteria and fungi from invading the subungual area."³³ No measurement was found of how much the nail protects the fingertip from blows, or of scratching as a defense. Dumontier's own summary is candid: "nail physiology in humans is not completely understood."³³

A window on disease, which is not a purpose

Physicians have read nails since Hippocrates described clubbing.¹⁷ Spoon-shaped nails prompt a blood count for iron deficiency.¹⁷ Beau's lines, grooves across every nail, mark a past severe illness; "knowing that nails grow about 1 mm every six to 10 days, the timing of the disease process may be estimated."¹⁷

This is a real use, but a use that physicians make of a part is not evidence of what the part is for. Blood pressure is also a diagnostic window. Nails show disease because they grow slowly from living tissue that records the body's condition, and any slow-growing record would do the same.

Part 5: Wet-finger wrinkling

It is driven by nerves

In 1973 the Dublin plastic surgeon Seamus O'Riain reported what a mother had noticed at bath time: after her child's nerve repair, the skin of the "denervated fingers did not "shrivel" like the normal fingers."¹⁸ He soaked patients' hands for 30 minutes at about 40°C and found that "denervated skin does not shrivel; it remains smooth."¹⁸ Changizi's paper traces the observation back to a 1936 paper by T. Lewis and G. W. Pickering.¹⁹

Einar Wilder-Smith and Adeline Chow measured blood flow during wrinkling in 2003 and concluded that it "is a function of digit pulp vasoconstriction."³⁴ The narrowed vessels shrink the pad, and the skin folds. The test has been used "for more than 80years" as a check on the sympathetic nerves,³⁵ and a 2026 review reports a sensitivity of 66% and a specificity of 70% for small-fiber neuropathy.³⁶ So wrinkling is not passive soaking. Whether it is for anything is a separate question.

The grip studies

Study	Design	Result
Changizi et al. 2011	Wrinkle patterns on "28 fingers from 13 hands" in online photographs	Pattern resembles drainage networks; grip not measured
Kareklas et al. 2013	20 people, each tested wet and dry, wrinkled and not; 45 marbles and weights	Submerged objects moved in 12% less time with wrinkles; no effect dry
Haseleu et al. 2014	Two groups of 20 on the same task, with different objects and hole heights; 38 tested for touch acuity	No benefit; one group slower with wrinkles, wet or dry; touch unchanged
Lin et al. 2015	Friction of wrinkled and smooth fingertips on plastic, dry, wet and under water	Abstract gives no result; full text not read
Davis 2021	516 museum visitors who chose their own group: dry, wet, or wrinkled; grip force on a load cell	Wrinkled fingers gripped wet objects with dry-finger efficiency

Changizi 2011. Mark Changizi and colleagues argued that the wrinkles "have been selected to enhance grip in wet conditions," because their channels drain water like the tread on a rain tire.¹⁹ Their evidence was the shape of wrinkles on "28 fingers from 13 hands" found online.¹⁹ They measured no grip, and wrote that they "only possess evidence for humans and macaques."¹⁹

Kareklas 2013. Twenty volunteers soaked their hands for 30 minutes at 40°C, then passed marbles and lead weights from a tub of water into a box. "With wrinkled fingers, transfer of submerged objects happened in 12 per cent (±2.3% s.e.m.) less time than with unwrinkled fingers," and wrinkles made no difference with dry objects.²⁰ The authors were careful: the study "does not, however, show how this is accomplished."²⁰ It supported a wet-handling benefit, not the drainage mechanism.

Haseleu 2014. Gary Lewin's group in Berlin ran the task "exactly as described by Kareklas" in two groups of 20, though with 52 objects of glass, rubber, plastic and brass instead of 45 of glass and lead.³ A power calculation on Kareklas's data said nine people should have been enough. Neither group showed a wet-object benefit. The second group was slower with wrinkled fingers on both wet and dry objects. Touch acuity was unchanged. They concluded that the task may be "not sensitive enough," and that measuring the force needed to pull an object from the fingers "would potentially be more suitable."³ This was a failed replication with a modified setup, not an exact one.

Davis 2021. Nick Davis ran the force test Haseleu asked for, on visitors to the Science Museum in London. Of 546 people, 516 were analyzed. Participants "allocated themselves to one of three conditions" and "were therefore not blind to their experimental condition."²¹ Wet fingers squeezed harder than needed; "wrinkly fingers reduce the grip force needed to grip a wet object, bringing that force in line with what is needed for handling a dry object."²¹ The sample is large, but self-selection and a mean age of 17.7 years are real weaknesses, and each person was tested in only one condition. Davis cites Haseleu only for its finding that touch is unchanged, not for its failure to replicate Kareklas.²¹

Lin 2015. Hsin-Ta Lin and colleagues in Taiwan measured the friction of wrinkled and smooth fingertips on plastic, dry, wet and under water. It is the only direct friction measurement on real wrinkled skin that was found. Its abstract ends "The experimental results revealed that how finger wrinkles affect grip action," without saying which way.²² The full text is paywalled and was not read, so it counts for neither side here.

Changizi's own verdict, to Smithsonian in 2015: "I don't think either study was good."³⁷ A 2017 review of wetness perception by Davide Filingeri and Rochelle Ackerley, written between Haseleu and Davis, called the grip question "still controversial."³⁸

Two things both sides have skipped. First, the comparative test: if wrinkling is a wet-grip adaptation, it should track wet habitats across mammals, not just ancestry. No such survey was found. Second, the cost: Kareklas suggested that constant wrinkling must cost something, and proposed lost touch sensitivity.²⁰ Haseleu found no loss. So the tradeoff that would explain why fingers are not always wrinkled is unknown.

Part 6: What creationists say

Body hair. David Menton of Answers in Genesis states the position most fully. "Evolutionists have long insisted that human body hair, and the small muscles (erector pili) attached to these hairs, are useless vestiges from our hairy ancestors. But human hair is as fully functional as that of any other mammal."²³ He names three uses. Long hair "would interfere with the evaporative water loss necessary for human thermoregulation by sweating."²³ All follicles "may be considered to be mechanoreceptors."²³ And follicles restore the skin surface, so that without them and sweat ducts "even routine skin abrasions might require a skin transplant."²³ Elizabeth Mitchell adds that "Hair follicles provide needed materials to heal damaged skin."³⁹ Lita Sanders of Creation Ministries International names sun protection and touch.⁴⁰ Jerry Bergman lists body hair among the structures that were once "considered vestigial" and now have "at least one function," without discussing it further.⁴¹

Priced against the data, each named use is real. Dean 2012 measured touch-based detection. Lasisi 2023 measured sun shading and the evaporation cost of dense hair. Rittié 2013 and Martínez 2016 measured follicle-based healing. Two claims go too far. Menton says "hair density per square inch is approximately the same on the human body as it is for most primates";²³ Kamberov found it equal to the chimpanzee and two- to 21-fold below the macaque. Menton's "skin transplant" line puts follicles and sweat ducts together, and Rittié's data put most of the weight on the ducts. Sanders's "a great deal of body heat is lost out of the top of the head" was not tested here and should not be repeated without a source.

Nails. Carlos Estrada of Creation Ministries International writes that "Fingernails help to judge how firmly to hold anything," summarizing the BBC article he is answering.⁴² Brothers and Hollins support that for strong grips. Sarah Eshleman of Answers in Genesis calls fingernails "our finest defenders" against itching invaders.⁴³ That is devotional writing, not a measured claim. CreationWiki says nails protect "the underlying skin and receptors of the toes and fingers," and that without them "these receptors would be exposed to damage and many harmful particles within the air."⁴⁴ The first half is plausible and unmeasured; the second has no source. The same page says a doctor may check nails "for signs of diabetes or amnesia."⁴⁴ No nail sign of amnesia is known, and the page's own list pairs spoon-shaped nails with anemia, which is probably the word meant.

Wrinkling. Mitchell wrote in January 2013, two weeks after Kareklas, that "wrinkles now have a proven functional value," and that "God designed your skin on your fingers to wrinkle that way so you could hold onto things underwater better."²⁴²⁴ One study does not prove a function, and the page, as archived in 2020, never mentioned the failed 2014 replication. The secular side made the same error: a 2026 neurology review cites Kareklas alone, describes it as a three-group design it did not use, and omits Haseleu.³⁶ A 2025 engineering paper opens by stating that wrinkling "is an evolutionary mechanism that increases grip strength in water."⁴⁵ No article on finger wrinkling was found from the Institute for Creation Research or Creation Ministries International.

Objections and responses

"Body hair is still a leftover. Its uses are trivial next to a coat." That is a different claim from "useless." The follicles are present at ape density. What changed is the hair each one makes. A creationist can say that a sweating, clothed animal is better off without a coat. An evolutionist can say that the coat was lost from an ancestor that had one. Both fit the follicle count. The follicle jobs, touch and repair, do not need a coat.

"The parasite study is tiny and has never been repeated." True. It is one study of 29 people, one parasite and one patch of skin. It shows that fine hair can help, not how much that matters in life. The touch function it rests on is not in doubt; the defensive payoff is.

"Follicles are not needed for healing. Palms heal fine." Correct, and this article says so. Follicles speed healing in mice and in ulcer grafts; in human forearms sweat glands carry most of the load. "Helps" is established. "Required" is not.

"A diagnostic window is not a function." Agreed, and Part 4 separates them. The nail's measured functions are sensory and mechanical.

"Haseleu refuted the grip hypothesis." Haseleu failed to reproduce one timing task with changed objects. Davis then found a grip-force benefit in a larger sample. Neither result is decisive.

"Davis confirmed it." Davis's participants picked their own group and knew which group they were in. A within-person, blinded force test, as Haseleu proposed, has not been published.

"If wrinkling is useful, why are fingers not always wrinkled?" Nobody knows. Kareklas guessed lost sensitivity, and Haseleu found none. Until the cost is found, the argument is incomplete on both sides.

Issues and unanswered questions

No comparative data on wrinkling. Changizi had evidence only for humans and macaques. Without a survey, neither design nor descent can say anything about its distribution.
Most nail studies are small or confounded. Shirato's fixed order, Seah's and Brothers's small samples, and Longo's two groups of 19 all need repeating. No measurement was found for protection or scratching.
Body-hair evaporation is unmeasured on bodies. The manikin tested scalp hair. Whether vellus hair helps or hinders sweating has not been measured.
One friction study is unread. Lin 2015 measured the friction of wrinkled fingertips directly. Its result could bear on the tread mechanism, and only its abstract was obtained.
Electric-field sensing is a capacity without a known use. It shows that fine hair is a working sensor. It does not show a purpose, and should not be offered as one.
"Useful" does not answer "inherited." Every measured function here is compatible with common descent. The chimpanzee-like follicle count, with the hair miniaturized, is exactly what descent from a furred ancestor predicts. A design account must explain it by function, as follicles for touch and repair, and that explanation is not a prediction.
The creationist literature has not updated. Answers in Genesis's wrinkling page and Menton's primate-density line both need correcting.

Verdict

The three features pass the parent's first test: each does measurable work. Body hair helps people notice crawling insects. Scalp hair shades the head. Follicles speed the repair of scraped skin, though sweat glands do more of it in human body skin. Nails are a sensory surface, a stiff backing for strong grips, and a small aid in picking up tiny objects. None of this rests on consensus; each claim comes from a measurement, and each measurement is small.

Wrinkling is different. Its nerve control is certain and clinically useful. Its purpose is not settled. Two studies found a wet-grip benefit and one did not, all three have design weaknesses, and a fourth was not read. "Probably real, probably small" is as far as the evidence goes.

On design against descent, these features are close to neutral. A furred ancestor explains the follicle count. A designer who wanted touch, repair and sweat cooling explains it too. A within-person force test, and a survey of wrinkling across wet- and dry-living mammals, would settle whether wrinkling has a use. They would not separate design from descent, because a designer and natural selection both predict that a grip aid follows wet habitats. What would favor descent is a feature whose distribution follows ancestry where function points elsewhere; what would favor design is the reverse. None of these three features has yet been measured in a way that separates the two.

Sources

1.
Darwin, Charles. The Descent of Man, and Selection in Relation to Sex, vol. 1. John Murray. 1st edition. 1871. Public domain. Darwin Online transcription F937.1, saved to the source library; pages read from its [page] markers.
1. 1a.
  Pages 24–25: “Man differs conspicuously from all the other Primates in being almost naked. But a few short straggling hairs are found over the greater part of the body in the male sex, and fine down on that of the female sex.” “There can be little doubt that the hairs thus scattered over the body are the rudiments of the uniform hairy coat of the lower animals.” The page marker for page 25 falls after "the hairs". ↩ ↩
2. 1b.
  Page 149: “Nevertheless, the fact that the other members of the order of Primates, to which man belongs, although inhabiting various hot regions, are well clothed with hair, generally thickest on the upper surface, … is strongly opposed to the supposition that man became naked through the action of the sun.” “I am inclined to believe, as we shall see under sexual selection, that man, or rather primarily woman, became divested of hair for ornamental purposes”. ↩
2.
Wiedersheim, Robert. The Structure of Man: An Index to His Past History. Macmillan. Translated by H. Bernard and M. Bernard. 1895. Public domain. archive.org OCR in the source library. Pages anchored by running heads and by the contents entry "Nails 11" and index entry "NAILS, 11".
1. 2a.
  Page 3: “Man is the least hairy of all the Primates ; indeed, his skin may be called almost smooth.” ↩
2. 2b.
  Page 11: “The nails of the fourth and fifth fingers (and especially the latter) most nearly suggest the claws of the lower animals, in being decidedly arched from side to side.” “On the under edge of the nail, between it and the ball of the finger, is found the last vestige of a structure which in the Apes is covered with a thickened layer of epidermis.” ↩ ↩
3.
Haseleu, Julia et al. “Water-Induced Finger Wrinkles Do Not Affect Touch Acuity or Dexterity in Handling Wet Objects.” PLoS ONE 9(1):e84949. Jan 2014. CC BY. Read from the PMC full text. Mirror: PMC
1. 3a.
  Section Abstract: “We found that skin wrinkling did not improve dexterity in handling wet objects nor did it affect any aspect of touch sensitivity measured.” ↩
2. 3b.
  Section Methods, Manual dexterity test: “exactly as described by Kareklas et al. [20]”. “The objects were 32 glass marbles of 16 mm diameter, 2 glass marbles of 23 mm diameter, 4 rubber balls of 26 mm diameter, 12 plastic dice with a side length of 16 mm, 2 brass weights of 200 g and 500 g.” Section Participants: “A power analysis of the original data by Kareklas et al. [20] revealed that a cohort size of 9 participants should be sufficient to detect the effect of skin wrinkling on handling wet objects.” ↩
3. 3c.
  Section Discussion: “The fact that we could not reproduce the results presented by Kareklas et al. [20] suggests that this manual dexterity test is not sensitive enough to tease out specific effects of wrinkled skin on performance.” “Measuring the force required to pull out dry and wet objects held between non-wrinkled or wrinkled fingers would potentially be more suitable to rigorously test the so called 'rain tread' hypothesis.” ↩
4. 3d.
  Section Discussion: “We suggest that wrinkling does not serve any adaptive function but rather is a byproduct of sympathetic nervous system-induced vasoconstriction that happens upon warm water-immersion.” ↩ ↩
4.
Kamberov, Yana G. et al. “Comparative evidence for the independent evolution of hair and sweat gland traits in primates.” Journal of Human Evolution 125:99–105. 2018. Read from the PMC author manuscript in the source library. Mirror: PMC
1. 4a.
  Section Discussion: “This finding suggests that the absence of visible fur cover in humans does not result from a loss of hair follicles per se, but instead favors a model of evolutionary changes in the morphogenesis of the individual hair follicles, which resulted in a shift from the large, pigmented terminal hair type characteristic of fur to the microscopic, unpigmented vellus hair type”. ↩ ↩
5.
Dean, Isabelle, and Michael T. Siva-Jothy. “Human fine body hair enhances ectoparasite detection.” Biology Letters 8(3):358–361. 2012. Read from the PMC full text. Copyright, Royal Society. Mirror: PMC
1. 5a.
  Section 1. Introduction: “The fine body hair of humans, composed of vellus hair and terminal hair, has little role in thermoregulation [8] and plays no significant part in sexual selection: it is frequently described as non-functional [2]”. ↩
2. 5b.
  Section 2. Material and methods: “Twenty-nine student volunteers in the University of Sheffield (10 females and 19 males) were recruited”. “Each volunteer was tested twice: once on one arm, and then a week later on the other.” ↩
3. 5c.
  Section 3. Results: “Host 'detections' were more frequent on unshaved when compared with shaved arms on male (paired t-test: t = 4.37, d.f. = 18, p < 0.001) and female (paired t-test: t = 4.11, d.f. = 9, p = 0.003) hosts”. “Bed bugs had significantly longer search times on unshaved arms compared with shaved arms on male (paired t-test: t = 3.79, d.f. = 18, p = 0.001) but not female hosts”. ↩ ↩
4. 5d.
  Section 4. Discussion: “Unfortunately, we could not distinguish between vellus hair and terminal hair in our study and sexual dimorphism in terminal hairs may be partly responsible for the higher hair index in males in this study.” ↩
6.
Lasisi, Tina et al. “Human scalp hair as a thermoregulatory adaptation.” PNAS 120(24):e2301760120. 2023. CC BY-NC-ND 4.0. Read from the PMC full text. Mirror: PMC
1. 6a.
  Section Abstract: “We find evidence for a significant reduction in solar radiation influx to the scalp in the presence of hair. Maximal evaporative heat loss potential from the scalp is reduced by the presence of hair, but the amount of sweat required on the scalp to balance the incoming solar heat (i.e., zero heat gain) is reduced in the presence of hair.” ↩ ↩
7.
Chapman, C. Elaine et al. “Perception of local DC and AC electric fields in humans.” Bioelectromagnetics 26(5):357–366. 2005. Abstract only, from PubMed (PMID 15887251); the full text is paywalled and was not read. Copyright, Wiley.
1. 7a.
  Section Abstract: “Sixteen subjects participated in the experiments, and none detected the local DC fields. In contrast, 9/16 subjects were sensitive to local AC electric fields”. “Subjects were unable to detect AC electric fields when the hair was removed from the forearm and hand, suggesting that the evoked sensation is mainly dependent on movement of hair located in the exposed region.” ↩ ↩
8.
Jankowiak, Kathrin et al. “The importance of hair in human perception of electric fields: a double-blind repeated measures study.” Scientific Reports 16:14970. May 13, 2026. CC BY 4.0. Read from the publisher full text, saved to the source library.
1. 8a.
  Section Abstract: “The findings indicate that hair plays a crucial role in EF detection, as removal of hair markedly increased detection thresholds for all EF types.” ↩
2. 8b.
  Section Results, Effects of relative humidity and hair removal: “The one-factorial rm ANOVAs on detection thresholds for DC … AC … and hybrid EF … with the factor test day (1, 2) showed a significant main effect for DC and hybrid EFs”. “but not for AC (p ≥ 0.13).” Section Methods, Test protocol: “Participants were instructed to remove all their hair from their head, arms, and face (beard hair) within 24 h before test day 2 by wet shaving.” Shaving always came before the second session, so order and practice are confounded with hair removal. ↩ ↩
3. 8c.
  Section Background: “Participants perceived average EF strengths of 25 kV/m DC and 15 kV/m AC under high-voltage power lines in the open field”. ↩
9.
Wyatt, Tristram D. “The search for human pheromones: the lost decades and the necessity of returning to first principles.” Proceedings of the Royal Society B 282:20142994. 2015. Read from the PMC full text. Copyright, Royal Society. Mirror: PMC
1. 9a.
  Section Abstract: “As humans are mammals, it is possible, perhaps even probable, that we have pheromones. However, there is no robust bioassay-led evidence for the widely published claims that four steroid molecules are human pheromones: androstenone, androstenol, androstadienone and estratetraenol.” ↩ ↩
10.
Ito, Mayumi et al. “Stem cells in the hair follicle bulge contribute to wound repair but not to homeostasis of the epidermis.” Nature Medicine 11(12):1351–1354. 2005. Abstract only, from PubMed (PMID 16288281); the full text is paywalled and was not read.
1. 10a.
  Section Abstract: “We show that ablation leads to complete loss of hair follicles but survival of the epidermis.” “After epidermal injury, however, cells from the bulge are recruited into the epidermis and migrate in a linear manner toward the center of the wound”. ↩ ↩
11.
Langton, Abigail K. et al. “An extended epidermal response heals cutaneous wounds in the absence of a hair follicle stem cell contribution.” Journal of Investigative Dermatology 128(5):1311–1318. 2008. Abstract only, from PubMed (PMID 18037901).
1. 11a.
  Section Abstract: “We find that in the absence of hair follicles cutaneous wounds heal with an acute delay in reepithelialization. This delay is followed by expansion of the region of activated epidermis, beyond that seen in normal haired skin, followed by appropriate wound closure.” ↩ ↩
12.
Martínez, María-Luisa et al. “Hair follicle-containing punch grafts accelerate chronic ulcer healing: A randomized controlled trial.” Journal of the American Academy of Dermatology 75(5):1007–1014. 2016. Abstract only, from PubMed (PMID 27745629).
1. 12a.
  Section Abstract: “Ulcer healing measured as the average percentage reduction 18 weeks postintervention was significantly increased (P = .002) in the hair follicle group with a 75.15% (SD 23.03) ulcer area reduction compared with 33.07% (SD 46.17) in the control group (nonhairy grafts).” “Sample size was small (n = 12).” ↩ ↩
13.
Rittié, Laure et al. “Eccrine sweat glands are major contributors to reepithelialization of human wounds.” American Journal of Pathology 182(1):163–171. 2013. Read from the PMC full text. Copyright, American Society for Investigative Pathology. Mirror: PMC
1. 13a.
  Section Introduction: “First, hair follicles in humans are of the lowest range of density among mammals, and the healing ability of individual skin sites does not correlate with their respective hair follicle density. Indeed, hairless areas of the human body such as the palms and soles have no inherent healing defects.” ↩
2. 13b.
  Section Results: “We counted 14.5 ± 0.6 eccrine sweat glands and 5.3 ± 0.6 pilosebaceous units per 4-mm diameter full-thickness biopsy sample of forearm skin (n = 12), corresponding to 115 ± 5 and 42 ± 5 average number/cm2, respectively”. ↩ ↩
3. 13c.
  Section Discussion: “Overall, our results demonstrate that i) eccrine sweat glands and pilosebaceous units contribute to the reepithelialization of human wounds by generating keratinocyte outgrowths that ultimately form new epidermis; ii) keratinocyte outgrowths expand at a similar rate whether they originate from sweat glands or pilosebaceous units; and iii) eccrine sweat glands outnumber pilosebaceous units by a factor close to 3.” ↩ ↩
14.
Seah, Benjamin Zhi Qiang et al. “Tactile sensibility on the fingernail.” Journal of Hand Surgery (American) 38(11):2159–2163. 2013. Abstract only, from PubMed (PMID 24206979).
1. 14a.
  Section Abstract: “The mean static 2-point discrimination, moving 2-point discrimination, and threshold value over the human nail were 6.7 mm, 2.4 mm, and 0.06 g, respectively. The corresponding values for the finger pulp were 2.4 mm, 2.2 mm, and 0.01 g, respectively.” ↩ ↩
15.
Longo, Matthew R. “Precise tactile localization on the human fingernail.” Proceedings of the Royal Society B 291(2026):20241200. 2024. Read from the PMC full text. Copyright, the author. Mirror: PMC
1. 15a.
  Section Abstract: “The results showed that participants are able to localize touch on the fingernails at substantially higher than chance levels. Moreover, the precision of this ability is not appreciably lower than that of the fingertips.” ↩ ↩
2. 15b.
  Section Introduction: “Another possibility, which has traditionally been emphasized, is that the fingernail provides a hard supporting background that enhances tactile sensitivity on the skin of the fingertip and helps to keep the fingertips from slipping when handling small objects [13,14].” ↩
16.
Brothers, Trevor, and Mark Hollins. “Two sensory channels mediate perception of fingertip force.” Perception 43(10):1071–1082. 2014. Abstract only, from PubMed (PMID 25509684).
1. 16a.
  Section Abstract: “To test this two-channel hypothesis in experiment 2, we hydrated participants' thumbnails in order to reduce nail rigidity and thus prevent stimulation of underlying SA-II mechanoreceptors. This technique was found to reduce sensory accuracy in a force-matching task at high forces (1000 g) while leaving low force matching (100 g) unimpaired.” ↩ ↩
17.
Fawcett, Robert S. et al. “Nail Abnormalities: Clues to Systemic Disease.” American Family Physician 69(6):1417–1424. Mar 15, 2004. Copyright, AAFP. Read from the publisher's HTML, saved to the source library; cited by section heading.
1. 17a.
  Section Introduction: “Clubbing, which is one example of a nail manifestation of systemic disease, was first described by Hippocrates in the fifth century B.C.” ↩
2. 17b.
  Section Koilonychia: “When spooning is present without an obvious associated illness, physicians should obtain a complete blood count and ferritin level to help rule out iron deficiency and hemochromatosis.” ↩
3. 17c.
  Section Transverse Linear Lesions: “Transverse linear depressions in the nail plate have been called Beau's lines since these lesions originally were described in 1846.” “Knowing that nails grow about 1 mm every six to 10 days, the timing of the disease process may be estimated by measuring the distance from the line to the nail bed.” ↩ ↩
18.
O'Riain, Seamus. “New and Simple Test of Nerve Function in Hand.” British Medical Journal 3(5881):615–616. Sep 22, 1973. Read from the PMC scan, saved to the source library. Copyright, BMJ. Mirror: PMC
1. 18a.
  Page 615: “Over two years ago the mother of a child who had had a nerve repair in the hand reported that she noticed at bath time the skin of the denervated fingers did not "shrivel" like the normal fingers, and that after repair shrivelling of the skin returned progressively from palm to tips.” ↩
2. 18b.
  Page 615: “It has been noted that after this procedure denervated skin does not shrivel; it remains smooth.” ↩ ↩
19.
Changizi, Mark et al. “Are Wet-Induced Wrinkled Fingers Primate Rain Treads?” Brain, Behavior and Evolution 77(4):286–290. 2011. The Karger copy is paywalled; read from the author's copy on changizi.com, saved to the source library. Its pages 1–5 are journal pages 286–290. It cites Lewis and Pickering, Clinical Science 2:149, 1936, for the nerve finding; that paper was not read. Mirror: Changizi.com
1. 19a.
  Page 286: “Wet fingers and toes eventually wrinkle, and this is commonly attributed by lay opinion to local osmotic reactions. However, nearly a century ago surgeons observed that no wrinkling occurs if a nerve to the finger has been cut. Here we provide evidence that, rather than being an accidental side effect of wetness, wet-induced wrinkles have been selected to enhance grip in wet conditions.” ↩ ↩
2. 19b.
  Page 286: “However, it has long been known that cuts to sympathetic innervation to a finger abolish the wrinkling response to wetness [Lewis and Pickering, 1936; O’Riain, 1973;”. Page 290: “Lewis T, Pickering GW (1936): Circulatory changes in fingers in some diseases of the nervous system”. The first passage is in the body text, not the abstract. ↩
3. 19c.
  Page 287, figure 2: “Smooth tires such as the racing tire (left) provide the best grip in dry conditions. In wet conditions, however, rain treads (right) are better.” ↩
4. 19d.
  Page 288, figure 4: “Wet-wrinkle networks on 28 fingers from 13 hands. These were found in the public online domain and were kept so long as the image was sufficiently sharp to see the wrinkles.” ↩
5. 19e.
  Page 290: “In the future, we hope to carry out (i) behavioral studies to see whether wrinkled fingers are superior to nonwrinkled fingers in wet conditions, and (ii) comparative studies to learn which mammals show the phenomenon (we currently only possess evidence for humans and macaques; fig. 1)”. ↩
20.
Kareklas, Kyriacos et al. “Water-induced finger wrinkles improve handling of wet objects.” Biology Letters 9(2):20120999. 2013. Read from the PMC full text. Copyright, Royal Society. Mirror: PMC
1. 20a.
  Section 3. Results: “With wrinkled fingers, transfer of submerged objects happened in 12 per cent (±2.3% s.e.m.) less time than with unwrinkled fingers. There was no difference in the time it took to transfer dry objects with or without wrinkles on the fingers”. ↩ ↩
2. 20b.
  Section 4. Discussion: “Our results are clear experimental evidence for the hypothesis that water-induced wrinkles improve the handling of submerged or wet objects. It does not, however, show how this is accomplished.” ↩
3. 20c.
  Section 4. Discussion: “The most likely explanation is that there must be a cost to wrinkled fingers that out-weighs its benefits under dry conditions.” “More likely, the cost may be in terms of a loss of somatosensory sensitivity in the fingertips or increased vulnerability to damage by catching on objects.” ↩
21.
Davis, Nick J. “Water-immersion finger-wrinkling improves grip efficiency in handling wet objects.” PLoS ONE 16(7):e0253185. Jul 21, 2021. CC BY. Read from the PMC full text. Mirror: PMC
1. 21a.
  Section Abstract: “The results showed that wrinkly fingers reduce the grip force needed to grip a wet object, bringing that force in line with what is needed for handling a dry object.” ↩ ↩
2. 21b.
  Section Participants: “participants allocated themselves to one of three conditions”. “Participants were therefore not blind to their experimental condition, but were naïve to the expected findings. 546 people initially took part in the experiment.” Section Results: “After automatic analysis of the force traces, 516 participants' data were analysed.” “the mean age was 17.7 (SD 13.1)”. ↩
3. 21c.
  Section Discussion: “Importantly, there is no difference in tactile sensitivity in wrinkled fingers compared to dry [16]”. Reference 16 is Haseleu 2014. The paper cites it nowhere else and does not cite Lin 2015. ↩
22.
Lin, Hsin-Ta et al. “Grip performance affected by water-induced wrinkling of fingers.” Tribology Letters 58(3):38. Jun 2015. Abstract only. The publisher page refuses plain downloads, so it was rendered in a headless browser and the abstract copied to the source library. The full text is paywalled and was not read. Copyright, Springer.
1. 22a.
  Section Abstract: “the coefficient of friction between the fingertip and the contact surfaces in the dry, wet and water-submerged states was evaluated using a tribometer (UMT-2)”. “The experimental results revealed that how finger wrinkles affect grip action.” The abstract ends there and states no direction of effect. ↩ ↩
23.
Menton, David N. “Vestigial Organs: Evidence for Evolution?” Answers in Genesis. Jul 7, 2014. Chapter 24 of The New Answers Book 3. Copyright. Web text saved to the source library; no print page numbers.
1. 23a.
  Section Erector Pili and Body Hair: “Evolutionists have long insisted that human body hair, and the small muscles (erector pili) attached to these hairs, are useless vestiges from our hairy ancestors. But human hair is as fully functional as that of any other mammal.” ↩
2. 23b.
  Section Erector Pili and Body Hair: “Indeed, hair density per square inch is approximately the same on the human body as it is for most primates.” ↩ ↩
3. 23c.
  Section Erector Pili and Body Hair: “Long body hair of the type seen on most mammals would interfere with the evaporative water loss necessary for human thermoregulation by sweating.” ↩
4. 23d.
  Section Erector Pili and Body Hair: “All hair follicles, regardless of size, are supplied with sensory nerves so that they may be considered to be mechanoreceptors.” ↩
5. 23e.
  Section Erector Pili and Body Hair: “Human hair follicles, regardless of size, serve as an important source of epidermal cells for recovering the skin's surface (reepithelialization) when broad areas of the epidermis are lost. If it were not for man's abundant hair follicles and sweat ducts, even routine skin abrasions might require a skin transplant.” ↩
24.
Mitchell, Elizabeth. “Wrinkled Fingers Get a Grip—but Not on Evolution.” Answers in Genesis. Jan 26, 2013. News to Note. The live address now redirects to a topic page; read from the Wayback capture of 28 September 2020, saved to the source library. That capture does not mention Haseleu 2014. Mirror: Archive.org
1. 24a.
  Paragraph 4: “Though precisely how they do so still remains a mystery, wrinkles now have a proven functional value.” ↩ ↩
2. 24b.
  Paragraph 9: “God designed your skin on your fingers to wrinkle that way so you could hold onto things underwater better.” ↩
25.
The five charges and the purpose, cost and alternative test are set out in Arguments from Bad Design, Part 1 ("A defect, an inherited feature, or a harmful purpose?") and Part 2 ("How to test a criticism"). ↩
26.
Wheeler, P. E. “The evolution of bipedality and loss of functional body hair in hominids.” Journal of Human Evolution 13(1):91–98. 1984. Not obtained; cited only for its title, from OpenAlex metadata and from Dean and Siva-Jothy 2012, reference 2. ↩
27.
Blanchard, Keith. “Why you should stop believing in evolution.” The Week. Aug 4, 2014. A pro-evolution essay despite its title; Blanchard was chief digital officer of the World Science Festival. The live address now returns an error; read from the Wayback capture, saved to the source library. Copyright. Mirror: Archive.org
1. 27a.
  Paragraph beginning "Listen, nobody wants to be related to monkeys.": “Why do you have sharp canine teeth? An appendix? Hair under your arms? If your body was designed for its current usage, there's a lot of inefficiency there.” ↩
28.
Coyne, Jerry A. Why Evolution Is True. Viking. 2009. Copyright; not stored. Read by search-inside on the print-disabled archive.org item; pages from the BookReaderJSIA leaf map (leaf 220 = p. 194), which also gives leaf 88 = p. 62, matching the book's index entry "goose bumps, 62".
1. 28a.
  Page 194: “As Linnaeus proposed, our anatomy places us in the order Primates along with monkeys, apes, and lemurs, all sharing traits such as forward-facing eyes, fingernails, color vision, and opposable thumbs.” ↩
29.
Torley, Vincent J. “Why Keith Blanchard really doesn't understand evolution.” Uncommon Descent. Aug 9, 2014. An intelligent-design blog reply to Blanchard 2014. Saved to the source library. Copyright.
1. 29a.
  Paragraph beginning "The last item cited as evidence for human evolution by Blanchard": “There are at least three hypotheses which attempt to account for why we have hair under our armpits: it may (i) aid the wicking of sweat away from the skin, (ii) reduce friction between the thorax and upper arm, or (iii) facilitate the release of sex pheromones”. ↩
30.
Takeo, Makoto et al. “Wound healing and skin regeneration.” Cold Spring Harbor Perspectives in Medicine 5(1):a023267. 2015. Read from the PMC full text. Copyright, Cold Spring Harbor Laboratory Press. Mirror: PMC
1. 30a.
  Figure 1: “At 8 d after wounding, re-epithelialization is completed and about 26% of re-epithelialized cells are lacZ+”. The caption reproduces Ito et al. 2005; lacZ marks cells descended from follicle bulge stem cells. ↩
2. 30b.
  Section Contribution of hair follicle stem cells: “From these results, it was concluded that hair follicle cells accelerate the onset of wound healing but are not necessary for wound healing.” ↩
3. 30c.
  Section Introduction: “Typically, wound healing in adult mammals results in scar tissue that lack skin appendages.” ↩
31.
From Rittié 2013's counts of 115 eccrine glands and 42 pilosebaceous units per square centimeter of forearm skin, with outgrowths from each expanding at a similar rate: 42 ÷ (42 + 115) = 0.27, about a quarter. This assumes each appendage contributes about equally, which the paper's rate finding supports but does not state as a share.¹³ ↩
32.
Shirato, Rikiya et al. “Effect of fingernail length on the hand dexterity.” Journal of Physical Therapy Science 29(11):1914–1919. 2017. CC BY-NC-ND 4.0. Read from the PMC full text. Mirror: PMC
1. 32a.
  Section Results: “The Wilcoxon signed-rank test showed that the mean times for the middle-sized sphere, small cube and pin with fingernails at 2 mm were significantly shorter than those with fingernails at 0 mm (p=0.03, p<0.01, p<0.01, respectively)”. Section Methods: “First, STEF times were measured after cutting the nails of the right thumb, index and middle fingers to 0 mm in length.” The 2 mm test always came second, 20 days later; the paper does not discuss a practice effect. ↩
33.
Dumontier, Christian. “Physiology of the nail apparatus: Surgical consequences.” Hand Surgery and Rehabilitation 43S:101654. 2024. Abstract only, from PubMed (PMID 38316211).
1. 33a.
  Section Abstract: “Unfortunately, nail physiology in humans is not completely understood.” “The hyponychium is the first barrier of defense preventing bacteria and fungi from invading the subungual area.” ↩ ↩
34.
Wilder-Smith, Einar P. V., and Adeline Chow. “Water-immersion wrinkling is due to vasoconstriction.” Muscle & Nerve 27(3):307–311. 2003. Abstract only, from PubMed (PMID 12635117).
1. 34a.
  Section Abstract: “Wrinkling was accompanied by significant reduction in blood flow velocity in all vessels, with a maximum in digital vessels. Our data show that water-immersion wrinkling is a function of digit pulp vasoconstriction.” ↩
35.
Wilder-Smith, Einar P. “Stimulated skin wrinkling as an indicator of limb sympathetic function.” Clinical Neurophysiology 126(1):10–16. 2015. Abstract only, from PubMed (PMID 25216595).
1. 35a.
  Section Abstract: “Skin wrinkling upon water immersion has been used as an indicator of limb nerve function for more than 80years.” “There is reasonable evidence allowing the test to be employed as a simple and effective marker for small fiber neuropathy and cystic fibrosis.” "80years" is the abstract's own spacing. ↩
36.
Fustes, Otto Jesus Hernández et al. “The skin-wrinkling test: principles and clinical applications.” Arquivos de Neuro-Psiquiatria 84(7). Aug 13, 2026. CC BY 4.0. Read from the PMC full text. Mirror: PMC
1. 36a.
  Section Studies involving the SWT: “examined 35 patients with SFN, among whom 23 showed absent wrinkling. In contrast, among 61 healthy controls, 43 demonstrated some degree of wrinkling in both hands. The sensitivity of the SWT was of 66%, with an specificity of 70%.” Reporting Datema and colleagues 2012. ↩
2. 36b.
  Section Physiology of wrinkling: “Volunteers performed grasping and object-transfer tasks under three conditions: dry fingers, wet fingers without wrinkles, and wet fingers with wrinkles induced by immersion.” Kareklas 2013 used a two-by-two design, wrinkled or not with dry or submerged objects; the three-group design is Davis 2021's. The review does not cite Haseleu 2014. ↩
37.
Ault, Alicia. “Ask Smithsonian: Why Do We Get Prune Fingers?” Smithsonian Magazine. Aug 6, 2015. Copyright. Saved to the source library.
1. 37a.
  Paragraph 11: “"I don't think either study was good," says Changizi, who hasn't gone back to studying pruney fingers again, but says that someone could probably do a better job of proving his theory.” ↩
38.
Filingeri, Davide, and Rochelle Ackerley. “The biology of skin wetness perception and its implications in manual function and for reproducing complex somatosensory signals in neuroprosthetics.” Journal of Neurophysiology 117(4):1761–1775. 2017. Review. Read from the PMC full text, saved to the source library; the HTML carries no printed page numbers. Copyright, American Physiological Society. Mirror: PMC
1. 38a.
  Section Peripheral tactile afferent input: “Finally, it is of interest to determine how physical changes of the skin due to prolonged wet exposure (e.g., water-induced finger wrinkles) impact tactile afferents and their functioning, although the implications of skin wrinkles for manipulative function are still controversial”. ↩
39.
Mitchell, Elizabeth. “Vestigial Organ Arguments: Useful or Unnecessary?” Answers in Genesis. Oct 22, 2011. Copyright. Saved to the source library. Mitchell is answering a Fox News list of useless body parts, which was not read directly.
1. 39a.
  Paragraph 6: “Yet human hair is not a non-functional relic of common ancestry with apes. Thick hair serves some animals for warmth and sun protection, but a thick covering of hair would impede the evaporation of sweat that God designed as the cooling system for humans. Most of the hair on humans is fine vellus hair, but it is not evolving away. All hair follicles are attached to sensitive nerve endings that detect nearby motion. Hair follicles provide needed materials to heal damaged skin.” ↩
40.
Sanders, Lita. “Badly designed arguments—'vestigial organs' revisited.” Creation Ministries International. Nov 25, 2011. Published under the name Lita Cosner. Copyright. Saved to the source library.
1. 40a.
  Section Body hair: “In addition, hair on the top of the head is useful for insulation (a great deal of body heat is lost out of the top of the head) and protection from sunburn. On other parts of the body, hair may have a sensory function; hair movement is transferred to sensory nerves within the skin.” ↩
41.
Bergman, Jerry. “Do any vestigial structures exist in humans?” CEN Technical Journal 14(2):95–98. 2000. Saved to the source library; page from the running head.
1. 41a.
  Page 96: “A list of some of the 180 structures that were considered vestigial in the early 1900's. It is now almost unanimously agreed that most of these structures have at least one function.” Figure caption; "body hair" is one of the listed structures. ↩
42.
Estrada, Carlos. “The incredible human hand: Naturally engineered or designed by intelligence?” Creation Ministries International. Nov 13, 2014. Copyright. Saved to the source library. Estrada is answering George McGavin's BBC article of 18 February 2014.
1. 42a.
  Paragraph 3: “Fingernails help to judge how firmly to hold anything.” ↩
43.
Eshleman, Sarah. “Creation Every Day: Atlas of a Scratch.” Answers 20(1). Jan 1, 2025. Copyright. Saved to the source library.
1. 43a.
  Paragraph 1: “The brain answers the call by prompting us to deploy our finest defenders: fingernails.” ↩
44.
CreationWiki. “Fingernail.” CreationWiki, the encyclopedia of creation science. Aug 12, 2014. The date is the page's "last modified" line. The live site did not answer; read from the Wayback capture, saved to the source library. Text under the GNU Free Documentation License. Mirror: Archive.org
1. 44a.
  Paragraph 1: “Fingernails (or simply nails) are a functional part of the integumentary system that protects the underlying skin and receptors of the toes and fingers. Without them, these receptors would be exposed to damage and many harmful particles within the air.” ↩
2. 44b.
  Section Personal Hygiene: “A doctor may even ask to check a patient's nails during a checkup in order to look for signs of diabetes or amnesia.” Section disorders list: “Koilonychia - caused by iron deficiency in the body; often accompanies anemia.” ↩
45.
Laytin, Rachel, and Guy K. German. “On the repeatability of wrinkling topography patterns in the fingers of water immersed human skin.” Journal of the Mechanical Behavior of Biomedical Materials 165:106935. May 2025. Abstract only, from PubMed (PMID 39965356). Copyright, Elsevier.
1. 45a.
  Section Abstract: “Finger wrinkling during and after water immersion, often called pruning, is an evolutionary mechanism that increases grip strength in water.” ↩