From Graham Cox
Charles Darwin suggested humans first stood up to free their hands to use tools. Kate Douglas says we know this “cannot be right since the oldest tools are a mere 2.6 million years old” whereas bipedalism arose 4.2 million years ago (24 March, p 36).
Who can be certain there are no older relevant stone tool finds to be made? And what of other materials? Many areas have no stone and certainly no flint. We may have stood up to more easily jab animals with poisoned sticks that were sharpened on rocks; preservation of such tools would be very unlikely.
From Elaine Morgan
Wading in water is the only known circumstance guaranteed to induce apes of all species to walk on two legs, even though in their case the process is still slow, clumsy and unstable.
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It is odd, then, that in considering why we lost our fur, Douglas’s main charge against the aquatic theory was that it “lacks fossil evidence to back it up” (24 March, p 39). That surely applies in equal measure to all the “why” theories.
Even odder is the objection that a waterside habitat would have rendered us more “round and lardy”. Indeed it would, and did. We have 10 times as many fat cells as do chimpanzees.
Mountain Ash, Glamorgan, UK
From Brian Horton
Douglas suggests that because pubic lice developed as a separate species (from gorilla lice) 3 to 4 million years ago, we probably lost our body hair about then. She also reports Mark Stoneking’s finding that body lice, which live in clothing, split from head lice only 72,000 years ago, plus or minus 42,000 years. This suggests humans did not wear clothes for about 3 million years after losing their hair.
But when humans first lost body hair they may have worn woven fig leaves – or other plants – which are an unsuitable environment for lice. Did head lice differentiate only when humans began wearing hats, offering a niche they could move into more readily? They could have moved when different clothing offered a suitable habitat.
West Launceston, Tasmania, Australia
Hothfield, Kent, UK
