As early hominins became bipedal the hands became free for other uses than transportation. My question is: which other use was most important?
My take: communication. I put forth that bipedalism allowed the hands to be used to develop gestural language which was eventually supplemented with vocal utterences and later virtually replaced by oral language. Tool use coevolved but the selective advantage of language drove the show.
Thoughts?
Dang!
Never finished my title! Mod please help! It was supposed to read “What was the most important handjob?”!!! So much for my marketing this thread.
Uh… most important handjob?
It made masturbation much easier.
Oh. Clever. I misread the OP to ask what was the biggest evolutionary development in humans, rather than the biggest advantage of being bipedal.
Some advantages of bipedalism:[ul][li]You stand taller, and are therefore more intimidating to predators who would otherwise attack you.[/li][li]You can throw rocks while running.[/li][li]You can carry things around for long distances.[/li]Having nothing else to do with your hands, you’ll waste time fiddling around with useless tricks like spear-making and fire-starting.[/ul]
I thought they discovered that there was once a species of ape that developed bipedalism, independently of the hominid line, which apparently never developed tool using.
[Moderator Hat ON]
Changed title to make it more clear, but did not add in the sexual pun, 'cause I don’t want to. 
Raising the tone and all that.
[Moderator Hat OFF]
Lumpy:
I think I know what you’re talking about-- it was a fossil discovered, I believe, near the Mediteranean. But it’s unclear if that species hung around long enough to get to the tool using stage. As far as we can tell, the hominid line was bipedal for 2-3 million years before tool use (other than chimp level, which probably wouldn’t be visible in the fossil record) became common.
An alternative theory (in moderate vogue circa mid-1980s, don’t know its status nowadays) goes (or went) like this:
The big human evolutionary jump was a single one that had many significant ramifications, and that jump was neoteny, the tendency of the mature creature to retain fetal or embryonic characteristics instead of finishing development as its ancestors would have. In this one jump, you get:
•_Architecture of the hip and pelvis, which would otherwise finish rotating around so as to make walking on all fours the default posture, remains in the “earlier” angle which supports walking upright;
• A similar lack of rotation of angles in the skull where it attaches to the spine, so as to facilitate a default position that faces straight ahead without neck flexion when one stands on all fours means that the skull remains in the “earlier” position where it faces straight ahead when one is standing up;
• The bones of the skull, which would otherwise fuse and finish ossifying to form a complete hard skull, do not do so, leaving the skull (at time of birth) soft and flexible. This does not cause, but does accomodate, a much larger brain case passing through a birth canal that had not grown spectacularly larger;
• The mental and development, which would otherwise be closer to a stage where the individual would fend for itself, remains significantly immature, requiring a much longer proportion of the lifespan to be spend dependent on the parent individuals. This sets the stage for much more complex learning and enculturation than would have developed if individuals were substantially self-sufficient at 3 or 4, and also makes the co-parenting relationship and the family organization more long-lived, making a better launching point for the development of complex social organizations;
• By being born “young”, the individuals have a substantially longer lifespan (measured cross-species by using parameters such as heartbeats-per-lifetime rather than years-per-lifetime) than any other creature on earth. (NOTE: for this item, competing theories include the evolutionary advantage to individuals of possessing still-living grandparents, insofar as possessing them increased the likelihood of being cared for, therefore passing along genes for longevity);
• A few unimportant aesthetic differences such as the infantile (in primate terms) shape of the jaw and brow; relative lack of body hair is also attributable to neoteny;
• Opposable thumbs, i.e., the architecture of the hand bones, which would otherwise mature to a more foot-like system of parallel digits, does not finish differentiating and rotating, and the thumb ends up stranded higher and off to an angle like a dewclaw–except of inimitable usefulness to us rather than of vestigial unimportance.
IANAPAA (I am not a physical archeological anthropologist)
Free hands with opposable thumbs allowed for the most important use for the hand (masturbation jokes aside) the creation and use of tools, our most fundamental physical skill.
Azael:
Freeing the hands (bepedalism) helps in tool creation, but it is not NECESSARY. Chimps routinely make and use a variety of tools. Clearly human tools are more sophisticated, but it is more likely that increased brainpower was the cause of more advanced tool creation. As I posted earlier, the hands were freed up millions of years before tool use increased significantly (as far as we can tell from the fossil record).
What drove brain and culture development more? Tool use or gestural (and consequently later spoken) language?
Society and human culture was not a direct result of indivuduqals making their own tools for their own use only. Human culture required communicating and passing on ideas both intra and inter-generationally. Improving upon them. And this ability to pass on ideas, such as but not limited to tool use, is the critical achievement that allowed for what we consider human accomplishment.
And oh thanks Gaudere, even if you don’t approve of my sense of humor.
(As Woody Allen said “Don’t knock masturbation, it’s sex with someone I love!”)
DS:
It is certainly plausible that gestural language predates spoken language (as Jean Auel postulated in her fiction works), but there is almost no way to prove it. So there’s really no use in arguing the point. There simply are no facts to base an argument on. Great speculation, but that’s it.
There are facts although you are right that proof is hard to come by.
The facts are based on evolutionary homologies. Speech production in humans relies on Broca’s area, located just in front of the motor cortex. In monkeys the homolg is an area involved in the visual guidance of motor acts, especially of hand actions. This is the area made famous for having so-called “mirror neurons” which respond when a subject sees an act performed by another and when the subject performs it him or herself. Which of course is the needed ability to learn to imitate how to use a tool and how to communicate in general. In humans Broca’s area is active during hand motions as well as with speech production. Furthermore surface impressions have been found on the skulls of Homo habilis specimens that correlate with an enlargement of the area corresponding to Broca’s area in modern humans.
Put together it is very suggestive that modern speech grew out of an older system originally designed to imitate the hand actions of others as in the use of tools and gestural communication. Which was then coopted by vocal production.
My guess is that the first bipedal ape reached down, picked up a rock or stick and beat the nearest ape over the head with it. We have been doing it ever since.
So what you really mean is that hominids were bipedal 2-3 million years before tool making. Tool use, as you’ve pointed out is already there with the chimps (e.g. throwing rocks and hitting things with sticks).
Tracer:
Acturally, no. Chimps make tools. Simple tools, but they definitely MODIFY sticks to use to fish for termites. They don’t just pick a stick up off the ground and use it as is.
:smack: