Human Evolution

Discussion in 'Biology & Genetics' started by sniffy, Oct 10, 2007.

  1. sniffy Banned Banned

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    Human Evolution
    Whatever your standpoint it is a beautiful thing so here. Children, please don't trash it.

    'Men with wide jaws, flared cheeks and large eyebrows were considered as sexy in the eyes of our female ancestors as they are today. Studies of fossils of our primate ancestors by reasearchers at University College London (UCL) and University of Cambridge showed that ancient ladies (sic!) helped to shape evolution by choosing sexual partners with those facial traits.

    "The evolution of facial appearance is central to understanding what makes men and women attractive to each other today," says palaeontologist Dr Eleanor Weston of UCL. "If you characterise masculinity by the simple ratio of dividing upper facial height by facial breadth, then attractive film stars do exhibit quite low ratios."

    Unlike other facial features, this difference cannot simply be explained in terms of men growing larger than women. The researchers also found a similar development in the chimpanzee male face. " This does support our findings in that this facial difference occuring at puberty must have important evolutionary implication, " says Weston....'
    BBC Focus magazine
    http://tinyurl.com/2napsu
     
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  3. spuriousmonkey Banned Banned

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    The grand topic of human evolution. Is there anything more beautiful than losing yourself in a debate on your own ancestry? No, or maybe it is the history of the xenathrans.

    The story of human evolution can be approached from many different angles all equally interesting, although some of them are just plain repulsive.

    Let's explore these approaches in this thread and let our minds wander (i was infected temporarily by Draqon).

    Why not start with this article:
    http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0020340

    Genetic Analysis of Lice Supports Direct Contact between Modern and Archaic Humans

    Parasite co-evolve with their hosts. By studying human parasites you can discover things about humans.

    The researchers found two extant lineages of human lice that diverged 1.18 MYA ago. Which was suprising because we were supposed to have gone through a genetic bottleneck ca. 0.05–0.10 MYA ago.

    There are tow main theories on origin of modern humans, Recent African Replacement and Multiregional Evolution.

    The louse data supports a compromise between the two models, the Eswaran's Diffusion Wave model.
    The researchers cannot say with confidence whether the different human lineages of Homo sapiens and Homo erectus were fucking with each other because:
    The researchers therefore suggest that maybe someone should look at pubic lice.
     
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  5. sniffy Banned Banned

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    I start with evolution of facial features and spurious lowers it to pubes. I give up!
    Hissy fit!
     
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  7. nietzschefan Thread Killer Valued Senior Member

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    Why are us narrow-faced villians still around then?
     
  8. spuriousmonkey Banned Banned

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    The puberty reference is rather interesting though. Apparently we are the only primate that goes through puberty. And we are not sure why.

    Puberty comes with a growth spurt, but that alone cannot explain it, because obviously a male Gorilla is larger than the male human which doesn't have puberty.

    Some people suggest that it is the other way around. We limit our growth during the first years because it would be detrimental to be large and learning at the same time. If you stay small and cuddly while still making many mistakes and learning proper behaviour you have a greater chance of survival, or at least not rubbing someone the wrong way.

    Maybe the answer is is facial structure?!
     
  9. sniffy Banned Banned

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    Humans have the most developed brains of all creatures. It takes many years to develop the brain. The body develops more slowly than the brain. Puberty is a way for the body to catch up with the brain?
    OOps I think i may have expressed an opinion....but I'll call it conjecture.
     
  10. spuriousmonkey Banned Banned

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    It is true that there is a large growth of brain matter during puberty. And what happens afterwards is that connections are being pruned. And then we become 'resonsible' adults.

    Regarding human evolution this is very interesting, because I have read some stuff that suggests that maybe we are the only human lineage with a puberty phase.

    there are some studies (based on very little data of course) that other homo lines might not have known puberty. They did this by comparing bone growth to tooth growth, because tooth growth is more uniform, and bone growth can vary more (as the growth spurt during puberty).

    But critics point out that there is a lot of variation within humans in this respect and since the datasets of other homo lineages is so limited we can't really make any conclusions, not even the one I posted in the previous paragraph.
     
  11. sniffy Banned Banned

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    As a 'resonsible' scientist can't you get some grant money to enlarge the datasets? I don't like science without conclusions.
     
  12. spuriousmonkey Banned Banned

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    it is not so easy to go and find a large collection of skeletons of homo erectus, or other human lineage even if you have the funds.

    Enlarging the dataset is therefore dependent on luck.

    Remember that there are still no fossils of the chimp ancestor!!!! (well, maybe there are, but not the last time I checked).
     
  13. sniffy Banned Banned

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    Oh well better carry on looking at genes then as therein lie all the answers.
    Or maybe we are the chimp ancestor.
     
  14. spuriousmonkey Banned Banned

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    Interesting that you say that. There are three options basically.

    the ancestor of the chimps and humans looked human.

    the ancestor of the chimps and humans looked like a chimp.

    the ancestor of the chimps and humans looked like something inbetween a human and a chimp.

    (and of course there are all the options in between for the continuous minded amongst us).

    yet, we automatically think the ancestor must have been like a chimp.

    And...was it?
     
  15. sniffy Banned Banned

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    Well what was the most recent common ancestor? Wasn't it more like a flying squirrel?
     
  16. spuriousmonkey Banned Banned

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    of chimp and humans?

    no, that was something about 6 million years old.
     
  17. sniffy Banned Banned

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    It was humanoid then? A hobbit?
     
  18. Enmos Valued Senior Member

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    Last edited: Oct 10, 2007
  19. spuriousmonkey Banned Banned

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    Probably chimp-like and the existence of bonobos and chimps give a clue.

    Chimps and bonobos look remarkably similar. So similar in fact that not so long ago they were mixed in zoos because they thought they were just all chimps.

    If the split between bonobos and chimps was very recently then we can't say if the ancestor between humans and chimps was chimp-like, or human-like.

    It turns out that chimps and bonobos split from each other about 3 million years ago. (or something in that order) In 3 million years they hardly changed. It seems reasonable to assume they haven't changed that much before that.

    The human lineage was 'radically' different 3 million years ago though. And therefore we can assume that the ancestor of chimps and humans was more chimp-like than human-like.
     
  20. Fraggle Rocker Staff Member

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    But you're just talking about the physical brain. With a massive forebrain like ours, there is a lot more synaptic development--learning--remaining to be done after the physical development is complete, than with other species. Our bodies are more or less mature around 17 or 18, but the synapses for making good judgments and tempering emotional reactions, which are required for successful, independent adult behavior, aren't complete for another four or five years.
    So look further. Next to one another, the closest relative to both humans and the two species of chimpanzees are the two species of gorillas. Which animal looks more like a gorilla, the human or the chimp?

    The massive brain case; the fully opposable thumb; the spine, musculature and shorter arms for full-time bipedalism; the proliferation of facial muscles useful only for non-verbal communication; the loss of fur; the buoyancy that allows us to swim easily; the little webs between our fingers which, in conjunction with that buoyancy, almost make us wonder if we were once aquatic; the reorientation of the vagina and pelvis permitting face-to-face copulation... I'd say Homo is more different from the other hominoids ("great apes," which also include the orangutan) than they are from each other. If the common ancestor of Homo and Pan already looked like Homo, it would be extraordinary for Pan to devolve, back into an ancestral appearance common to all other hominoids.
     
  21. James R Just this guy, you know? Staff Member

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    Genetically, if I recall correctly, that is not true. Humans are closer to chimps, for example, than either is to gorillas.
     
  22. spuriousmonkey Banned Banned

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    You are quite right, and trees build on physical and behavioural characteristics show the human lineage sticking out with several magnitudes from the other apes.
     
  23. sniffy Banned Banned

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    Just go back to the top of the page and have a look at the study which highlights an evolutionary preference for wide jaws, flared cheeks and large eyebrows in men. The research team found similar patterns in chimpanzees.
     

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