If they weren't, would not people be born without them?
The likely reason for the presence of fingernails and toenails is that they are useful. Fingernails help humans to scratch things, peel fruit, open things, pick away the outer layers of other edibles, undo knots, and perform a variety of other tasks. In a more distant past, fingernails probably assisted humans with the capture of body lice, as is still seen among the great apes. When the feet were used more like hands, toenails served a similar function, helping early humans to open vital food objects, strip bark to build structures, and other such things.
1) It is not the case that every trait possessed by every organism necessarily has an adaptive function.
2) If anything, toenails are a byproduct of development, not evolution. The same sets of genes control the growth of fingers and toes (thus the many similarities between them). Fingernails, being possibly advantageous, might well be selectively maintained, but that means bringing toenails along for the metaphorical ride even if they serve no obvious purpose. Similar to the reason male humans have nipples, etc.
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1) It is not the case that every trait possessed by every organism necessarily has an adaptive function.
2) If anything, toenails are a byproduct of development, not evolution. The same sets of genes control the growth of fingers and toes (thus the many similarities between them). Fingernails, being possibly advantageous, might well be selectively maintained, but that means bringing toenails along for the metaphorical ride even if they serve no obvious purpose. Similar to the reason male humans have nipples, etc.
Your thoughts on this? Make a comment...
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