patiodog wrote:I dunno. But generalist is a strategy too, ain't it? (And ain't all mammalian scavengers generalists of a sort? Wolves will scavenge, and hyenas will hunt, depending on circumstances.) Just vaguely remembering reading about the idea we evolved to exploit scavenging opportunities at the edge of the African woodlands, and we turned out really weird as a result -- upright, so we would be exposed as little as possible to the midday sun that renders other animals inactive... and a host of other traits that escape me right now. (I've been up for almost 40 hours and am starting to wind down...)
Any chance of more on this when you have rested????
dlowan wrote: Anyhoo - I suspect that apes - if we allow them to live - will gradually develop greater intelligence and more tools and such. I am fascinated by the notion that apes taught language might, if there are enough of them, do a little mini-leap in their small group.
Unless it is a symbiotic relationship the rule is generally one species per niche. The better adapted one drives out the lesser adapted one.The only other species that came close to occupying the culture niche was Neanderthal. They were quite successful until Homo sapiens (us) showed up and they are no longer here. It is ours, we won it (perhaps not fair and square) and we are unlikely to give it up.
good point rabbit. we never view any products of evolution because its still busy selecting for and against.
did our brain grow due to a genetic mutation? or did it grow because of a high Vitamin b and protein diest? or did one condition facilitate the other.
acquiunk-your students take is reminiscent of the Gallagher line
'we didnt evolve from the beings who got killed and whose fossils we see in africa, no, we evolved from the fast little f*ckers who made it back to the cave."
as far as tool making being a marker of our evolution, remeber that, based on mary leakeys digs A. boisei and earlier "Southern apes" used tools that showed some degree of crude working. however , toolmaking just languished in one level for over a million and 900 thousand years or more before newer , more clever , markings like fluting and careful knapping, and symmetry showed up.tool making (as opposed to just using), all of a sudden blossomed into tool typology which, besides DNA,and linguistics, help us mark the movements of populations around the planet. then, specific packs of alleles in the junk of a populations genome (average populational gene expression) show traits that become enhanced and enable us to "date" a populations arrival and expansion in a particular geographical area. These "junk DNA" packs are like a unique bar code of a local population.when wwe combine tool typology, DNA coding, and the linguistics evolution we can almost peg the time and date of a populaations arrival at a remote site.
Then , we go and mess up the perfect fingerprint of a population by turning theentire world into a big musical chairs experiment. fortunately, the DNA encodes and remembers our travels , so like a hard drive, our DNA keeps where we were intact in the memory but allows new alleles to develop that , after enough generations, show new bars encoded
hey set, good ta see ya back. Im goin to Canadia this week. izzit cold yet? .
Quote:Unless it is a symbiotic relationship the rule is generally one species per niche.
This has been very elegantly demonstrated in test tubes -- though the principle seems to apply to bigger organisms as well. The key to diversifying (if you were making a conscious decision to do so) is to move into an unexploited niche. Sometimes this is very subtle; two species of insect, for instance, might live on the same leaves of the same type of bush, but depend on different parts of the leaf for shelter and food.
Quote:Any chance of more on this when you have rested????
a'right, here's what I read -- non-peer-reviewed hearsay from John Reader's "Africa: A Biography of the Continent."
Quote:The fossil evidence conclusively shows tat the ancestors of the hominid lineage existed only in Africa; therefore, our body-cooling system must have been an adaptive response to the environmental stresses of tropical Africa. ... The significance of this conjunction has been explored by Pete Wheeler in research undertaken for a doctoral thesis.
Wheeler investigated the physiological aspects of hominid evolution from a functional point of view, assessing the basic capabilities and essential requirements of the ancestral hominid, and endeavouring to define the selective pressures and adaptations that had moulded ancestral characteristics into modern human form. His research led to a string of publications which ultimately invite the conclusion that thermoregulation is at the root of all things human.
He began with assessments o the basic -- even rather obvious -- physiological attributes of the human form. For instance, since the epright bipedal gait bestows little avantage in terms of locomotive efficiency {addressed earlier in the book}, could it be that the upright stance is functionally advantageous in terms of heat load and cooling demands? Clearly, an animal walking upright exposes less of its body surface to the direct rays of the sun than an animal moving about on all fours, but ow much difference does it make?
Wheeler made models of hominids which could be positioned in bipedal and quadrupedal mode and measured the area of their body surfaces that was exposed to direct solar radiation as the sun rose and fell through the course of the day in tropical Africa. The results showed that while the quadruped had around 20 per cent of its body surface exposed to the sun throughout the day, the biped started off with 20 per cent surface exposure but this declined rapidly as the sun rose. By noon, when the sun was directly overhead and solar radiation at its most intense, only 7 per cent of the biped's body surface was exposed to te sun. This meant that simply by standing upright, the bipedal hominids avoided 60 per cent of the direct solar radiation to which they would have been exposed as quadrupeds.
Furthermore, since wind speeds rise and air temperatures fall with distance above the ground, the upright stance exposed a greater proportion of the body to conditions under which relatively more heat was removed from the skin by convection. Wheeler measured the cooling effects of elevation above ground and found that a biped standing on an open grassy plain lost heat 33 per cent faster than a quadruped in the same location. And this benefit was further enhanced by the fact that the air at ground level was relatively humid, owing to water given off by transpiring vegetation. Consequently, although the quadriped may have sweated as much as the biped, the sweat would no evaporate as quickly and its cooling effect therefore was diminished.
This is all couched amid a discussion of the benefits of a large brain -- and a brain organized so that it could work with symbols, plan ahead, and whatnot -- to an animal that had to travel long distances through harsh conditions to get to food sources, be they "scavenged" (i.e., carcasses) or dug up (edible roots, nuts, and tubers that are relatively abundant in the part of Africa where hominids grew up).
Oh good - I will read after work...
farmerman wrote:hey set, good ta see ya back. Im goin to Canadia this week. izzit cold yet? .
We were in eastern and northeastern Ontario. Temps ran from freezing to about 60 flabbergrotzhen. Rain off and on for the last week. They got about ten inches of snow out in the prairies, but none in the east. The weather will be chilly, but is supposed to dry out this next week. Beautiful foilage (to quote Marge Simpson) . . .
Im flyin to Lake Melville in E Labrador to look at a claim. Im takin no chances with the weather. We leave tomorrow.
Well, you'll be more than a thousand miles east of where we were. I think the trend will be chilly and wet, but not snow yet, except perhas "ocean effect" snow.
The story here is also hominids about 2 million years ago.
Endurance runners have evolved to humans..
Quote:Marathoners at a really early age
About 2 million years ago, humans began to jog - perhaps to hunt animals or scavenge carcasses on the vast savannahs of Africa. And the ability to run long distances shaped our anatomy, allowing us to evolve from apelike ancestors and making us look the way we do today, concludes a study in this week's issue of Nature.
"We are very confident that strong selection for running - which came at the expense of the historical ability to live in trees - was instrumental in the origin of the modern human body form," says University of Utah biologist Dennis Bramble, who wrote the study with Harvard anthropologist Daniel Lieberman. "We think running is one of the most transforming events in human history."
That conclusion runs contrary to the conventional theory that running simply was a byproduct of the human ability to walk. Humans are poor sprinters compared with other running animals, which is partly why many scientists have dismissed running as a factor in human evolution. But "high speed is not always important," Dr. Bramble says. "What is important is combining reasonable speed with exceptional endurance."
source-CSMonitor
