0 Members and 1 Guest are viewing this topic.
quote:Originally posted by GordonPquote:"You are also assuming an efficiency that does not exist in nature." .On the contrary, many animals have clearly defined territories which they guard jealously.
quote:"You are also assuming an efficiency that does not exist in nature."
quote:quote:"But why would the dominant male always have the mutated gene"? Because the mutated gene gives an obvious advantage in a fight for the right to be dominant male.
quote:"But why would the dominant male always have the mutated gene"?
quote:True if we are talking about one mating but if the mutated male has almost inclusive rights to all the females in the group then we are talking about 50% of the next generation carrying the gene. He maintains almost exclusive rights because of the advantage he has in personal combat due to his mutated gene. His successor in the next generation will almost certainly carry the gene and have the same advantage. When he starts mating with his generation of females 50% of them will also be carrying the gene, so any mating such a female will result in 100% of the offspring carrying the gene and 50% of his offspring will carry the gene when mating with a female that does not carry the gene. Therefore 75% of the next generation will carry the gene. Allowing for the odd bit of hanky-panky by the other males, 50% of which will be carrying the gene anyway, let's say 60% of the second generation. By the 4th or 5th generation the gene will be carried by 99% of the group.
quote:quote:Originally posted by GordonPDarwin said that evolution is very much like the life of a soldier, long periods of time pass when nothing much happens, interspersed with short periods of frantic activity.I believe I read that in "Origin of the species" or it may have been in "The descent of man". Also the quote may not be word perfect but the meaning is clear.
quote:Originally posted by GordonPDarwin said that evolution is very much like the life of a soldier, long periods of time pass when nothing much happens, interspersed with short periods of frantic activity.
quote:Punctuated equilibrium (or punctuated equilibria) is a theory in evolutionary biology which states that most sexually reproducing species will show little to no evolutionary change throughout their history. When evolution does occur, it happens sporadically (by splitting) and occurs relatively quickly compared to the species' full duration on earth. Punctuated equilibrium is commonly contrasted against the theory of phyletic gradualism, which hypothesizes that most evolution occurs uniformly and by the steady and gradual transformation of whole lineages (anagenesis). Punctuated Equilibrium's HistoryPunctuated equilibrium originated as an extension of Ernst Mayr's concept of genetic revolutions by peripatric and allopatric speciation. Although the workings of the theory were proposed and specifically identified by Mayr in 1954, most historians of science recognize Niles Eldredge and Stephen Jay Gould's 1972 paper as the principal source of its acceptance (by both paleontologists and evolutionists) and as the foundational document of a new and serious paleontological research program (Mayr 1992: 25-26, Shermer 2001: 102-113). Punctuated equilibrium differed from Mayr simply in that Eldredge and Gould had placed considerably greater emphasis on stasis, whereas Mayr was generally concerned with explaining the morphological discontinuity (or punctuational patterns) found in the fossil record.The Eldredge and Gould paper was presented at the Annual Meeting of the Geological Society of America in 1971. The symposium focused its attention on how modern microevolutionary studies could revitalize various aspects of paleontology and macroevolution. Tom Schopf, who organized that year's meeting, assigned Stephen Jay Gould the topic of speciation. Gould recalls that "Eldredge's 1971 publication [on Paleozoic trilobites] had presented the only new and interesting ideas on the paleontological implications of the subject—so I asked Schopf if we could present the paper jointly." (Gould 2002: 775) They did. According to Gould "the ideas came mostly from Niles, with yours truly acting as a sounding board and eventual scribe. I coined the term punctuated equilibrium and wrote most of our 1972 paper, but Niles is the proper first author in our pairing of Eldredge and Gould." (Gould 1991)
quote:Originally posted by GordonPI have over simplfied the theory in order to save typing.Of course a group will never defend it's territory with 100% success but it is not neccessary for the group to be totally isolated. Indeed I have said that the gene pool may have been affected by capured females. This will not matter in the long run.Point two. The mutated gene does not have to offer an advantage in every situation. But only in a fight to be dominant male. In such a situation the ability to stand upright longer than your opponant offers a massive advantage when you have a weapon like a baseball bat in your hand. Even if the other male picks up such a weapon his inability to stand upright for more than a few steps makes the weapon almost usless. The male with the mutated gene will win every time.x and y. After many generations x is walking almost upright most of the time. They still eat almost anything edible. x eats y.Despite the comlexities of reproduction it is neccessary only for the ape with the mutant gene to father a significant number of the next generation. As one of the next generation with the gene will become dominant male (as I have explained above) the gene will quickly dominate the gene pool. We are talking about a group with a population of perhaps 15 to 20, or less.
quote:Regarding the Darwin quote, it doesn't really matter where I read it.
quote:Originally posted by GordonPPerhaps I've not made myself clear. I never intended to infer that all the apes disappeared, obviously the rest of the apes are still with us. All am am trying to say is the within the group the apes with the mutation outbread those that did not posses it. And either infiltrated other similar groups with the same result or killed them.
quote:Originally posted by GordonPInteresting discussion. Try this for another hypothetical senario.The climate in North Africa starts to change, as the years pass the forest retreats to central Africa and all the apes, dependent on the trees for safe haven, retreat with the forest. One particular species begin to spend most of their time on the fringes of the forest, already a user of tools (they use stones to break open nuts)they begin to scavenge on the remains of kills left by the preditors that now inhabit the open areas, using their tools to break open the bones which remain behind in order to get at the bone marrow.They live in small family groups led by a dominant male, usually the biggest and strongest male. The groups comprise, the dominant male, several adult females, the young and several adult subordinant males. The dominant male regards the adult females as his wives and guards them from the other males. They are still reliant on the trees for safe haven from preditors and only venture onto the open ground while one of the group is in position high in the trees as a watchout.So far nothing has happened to effect the evolution of the species.One day a male is born with a slight mutation, nothing spectacular, just a deformation of the pelvic bone. He still moves about most of the time with his knuckles almost brushing the ground but he can do something none of the rest of the group can do, he can take many steps in an almost upright position, the rest of the group can manage only three or four steps in this position before dropping their hands to the ground. (As with many apes today).Eventually he approaches maturity and driven by testosterone challenges the dominant male. Not yet fully mature his chances of success are practically nil and being something of a lightweight will probably always remain so.As the two face each other he does something that has never been done before, he picks up a short stout piece of broken branch, stands almost upright and closes in on the dominant male who also stands almost upright in defiance. After a very short while dancing around the dominant male can stand upright no longer and drops his hands to the ground, he is now defenceless. The young male knocks seven bells out of him and takes over the harem.Something new has happened, an ape has used a tool as a weapon, and changed the path of evolution. Now it is not the biggest and strongest who rules but the one who can stand upright the longest. As the ruler of the group has the females to himself his genes will predominate the next generation and so on and so forth.G W Pipes
quote:Originally posted by xethoPeople didn't evolve from apes, we shared a common ancestor.That common ancestor wasn't overly specialized for a life in either a forested or open environment. The ones that ended up living primarily in grasslands eventually became humans, the ones that lived in forests became monkeys.
quote:Originally posted by thebrain13I think the key issue is defense. It's been brought up that taller creatures can see more prey, but on the flip side more predators can see you. if you look at when the dinosaurs roamed the earth you might notice that most of the carnivores walked upright, while most of the herbivores walked on all four.
quote:The diet is another advantage to walking upright. Herbivores need to eat a lot more then carnivores so they have more weight to carry around.
quote:Originally posted by another_someonequote:Originally posted by thebrain13I think the key issue is defense. It's been brought up that taller creatures can see more prey, but on the flip side more predators can see you. if you look at when the dinosaurs roamed the earth you might notice that most of the carnivores walked upright, while most of the herbivores walked on all four.This no doubt explains why giraffes and elephants are so short, and why kangaroos walk on all fours, or why lions walk on their hind legs.quote:The diet is another advantage to walking upright. Herbivores need to eat a lot more then carnivores so they have more weight to carry around. This part is true, so carnivores tend to be sleeker, but they are no more likely to be bipedal (in fact, a bipedal cheetah would not run as fast).Back to your issue of defence, there is one point that may be relevant, and that is communal defence. Many social animals will post lookouts that give the social group an early warning of danger, and allow them time to prepare a communal defence against the threat. For these animals, particularly given the high visibility that inevitably derives from having a large community of animals congregating together, early detection of a threat is more important that camoflage.George