Re: Hands and human evolution

[Adam Rose <adam@xxxxxxxx>]

Adam wrote:
>
> "Apes all have thumbs which curve in the same direction as their
> fingers - for  the simple reason that it's easier to hang on to a
> tree with five fingers than four. We don't -  why not ?

Tom Condit wrote:
>
> Actually, our hands have the shape which biologists call
> "primitive reptilian pentadactylism", which is to say that they
> are shaped like those of lizards.  Most of the more primitive
> primates (monkeys, lemurs, etc.) share this characteristic,

But what about our nearest genetic relatives eg chimps , bonobos.
I'm sure we have an opposed thumb and they don't - am I right ?

I'm sure our thumbs developed as a result of tool production and
use, as did the brain, and that they are different from our nearest
relatives.

>
> Incidentally, on a point someone else (Mark Luckett?) raised, our
> cousins the chimpanzees and bonobos also use tools.  The big
> brain does *not* come first.  (And I promise another post on
> exactly this subject later this week--I've been putting it off
> for a month now.)
>

I saw a program on TV last night on Boxgrove Man, a site in the South
of England. It went through the evidence suggesting that dates the finds
to at least 500,000 years ago.

They found flints and carcasses which had been methodically butchered, 
suggesting
that these hominids did not fear any of the other animals around such a tigers.

Crucially, they found the base of an antler which had been used to produce the 
flints.
These hominids had found the antler and converted it into a tool producing tool.
They had decided to do this well before they came into possesion of the rhino 
they
had been butchering. This needs forethought and consciousness as well as 
technical
ability.

The program seemed unsure whether they existed before, at the same time as, or 
after
Neanderthals. On balance it seemed to suggest before / at the same time as.

Either way, hominids were producing tool producing tools 500,000 years ago, 
after
the brain had expanded to a certain size but by no means at the end of its 
evolution.

Interestingly, the program argued that humans supported the energy requirements 
of
a big brain by simply reducing the size of the gut, so the overall energy 
requirement
stayed the same. This in turn required higher quality food - ie, large amounts 
of meat.

But for a small animal like a human to kill a large animal like a rhino and then
defend the kill from other predators requires a high level of technical and 
social
ability. So groups with this sort of ability would be more likely to survive.

Adam.

Adam Rose
SWP
Manchester
UK


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