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Early hominid spreading and extinction

  1. Jun 11, 2016 #1
    Dear PF Forum,
    I've been wondering about this one thing in the extinction of early hominid.
    Homo erectus
    Homo habilis
    Australopithecus.
    They were all extinct.
    Why?
    Who killed them? What killed them?
    I read that the spreading of homo erectus (2 million years ago?) reached China and Java.
    Did homo sapiens kill them?
    If so, they (homo erectus) spread accross the world, did homo sapiens really kill them all?
    Or homo erectus evolved to become homo sapiens?

    Just in case anybody have any idea :smile:

    Thanks you very much.
     
  2. jcsd
  3. Jun 12, 2016 #2

    SteamKing

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    It's doubtful that H. erectus was killed off by H. sapiens, since the latter didn't evolve until about 200 K years ago. It's not like H. erectus showed up in what is now China one morning, found a bunch of modern humans already living there, and were subsequently wiped out, because modern humans didn't exist that far back in time.

    There's a handy chart of human evolution included with this article:

    https://en.wikipedia.org/wiki/Timeline_of_human_evolution

    There could be a number of factors why there aren't tribes of H. erectus or Australopithecus running around today. The climate of the earth has changed over time, meaning that groups of older hominids which once thrived were driven out of existence when they could no longer find food. Certainly, competition between older, less evolved human species and newer human species could have played a part in the disappearance of the former over time.
     
  4. Jun 12, 2016 #3

    Baluncore

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    That certainly is an interesting question, but is it really necessary to provide an answer and attribute blame?
    How certain could a jury of scientists from a different species ever be?

    Fictional murder mysteries always start with a victim and end in the discovery and exposure of the murderer. In the fossil record we only see evidence of individual victims. We can identify the disease burden or cause of death of individuals, but I doubt we can ever extrapolate that across an entire population or species.

    A species that succeeds during good times, may suffer in difficult times and finally become isolated in geographical pockets. Those diverse pockets may have different reasons for later population reduction and final extinction. The loss of community structure and the advent of cannibalism within the species may play a part at the end.

    Given the paucity of data, it would be a mistake to think we could identify a general reason for the extinction of an entire species. Written history is unreliable at the best of times, so I think we must settle for a few doubtful stories about the zoo exhibits, pets and livestock of our most distant ancestors.

    Meanwhile our individual and group actions may be leading to the extinction of our own species. Who will the last individual blame for their loneliness, the poor decisions made by our species, or the disease or predator that took the second last individual?
     
  5. Jun 12, 2016 #4
    Thanks for the chart.
    I think that makes sense.
    I would imagine that over time, since 70k years ago, when Homo Sapiens out of Africa, they encountered some older species and competed for food and space. But we can't find the fossil of the older species.
     
  6. Jun 12, 2016 #5
    That makes sense. I think it's not a mystery after all.
     
  7. Jun 12, 2016 #6

    SteamKing

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    At that period in time, there were two major groups of Homo alive and apparently living in close proximity to one another: H. sapiens and H. neanderthalensis.

    https://en.wikipedia.org/wiki/Neanderthal

    There is evidence that some Neanderthals and modern humans interbred at times, preserving some of the genetic material of the Neanderthals into modern populations.

    There is another group of humans which lived during this time, the Denisovans, but too little is known about them, since only fragmentary remains have been recovered from caves in Siberia:

    https://en.wikipedia.org/wiki/Denisovan

    Because they became isolated on an island in what is now Indonesia, H. floresiensis (hobbit man) was able to survive into relatively recent times:

    https://en.wikipedia.org/wiki/Homo_floresiensis
     
  8. Jun 13, 2016 #7
    Well there is quite a bit of genetic evidence of interbreeding between anatomically modern humans, neadethals and denisovians so we must have been able to coexist with at least some of our close hominid cousins. I don't know about erectus, but he would have been a pretty formidable adversary due to his size and strength. More likely a variety of factors conspire to make a species extinct. There were claims a few years ago that we almost went extinct with human population dropping to 10,000 or so, but it looks like this idea is no longer popular.
     
  9. Jun 13, 2016 #8
    https://en.wikipedia.org/wiki/Toba_catastrophe_theory Because of this?
     
  10. Jun 13, 2016 #9
    Yes, that's it. But it looks like DNA studies from the last 5 years have made this idea unpopular.
     
  11. Jun 14, 2016 #10

    jim mcnamara

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    Try 'not applicable' instead of popular. What you are discussing is called a genetic bottleneck. Modern cheetah populations have very low genetic diversity because of a recent near-extinction event for many populations. Some few members of the species survived. Near-extinction causes the bottleneck.
    This has happened in human populations as well. Example: Navajo populations were dramatically reduced by the US cavalry and the 'Longest Walk'
    https://en.wikipedia.org/wiki/Long_Walk_of_the_Navajo

    Here is a Freshman Bio take on this topic (part of the founder effect concept)
    http://evolution.berkeley.edu/evolibrary/article/bottlenecks_01
     
  12. Jun 14, 2016 #11

    jim mcnamara

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    Brief comments:
    1. Anthropologists were constrained for years by lack of solid non-conjectural proof about early man. So we've got lots of "species" of humans on the books.

    2. With the advent of good DNA sequencing some of that 'species list' will be revised as more material is found/analyzed.

    3. In a sense 'they' are us. Neanderthals buried their dead, for example, and used red ocher apparently ceremonially on the dead. Northern Europeans have about 4% of their DNA derived from Neanderthals.

    4. Long time separation does not preclude the immigrant populations from interbreeding with the resident populations.
    Example: Older resident Northern New Mexican folks of Spanish descent have about 30% of their DNA from native North Americans. The folks that came to the American SW from Spain in the early 1600's had been separate from locals for a minimum of about 14000 years.
    (edit to keep Stephanus happy)
     
    Last edited: Jun 24, 2016
  13. Jun 14, 2016 #12
    We can extract DNA from fossil?
    hm...
    Here? You mean the New World? :smile: I don't know. The people who came
    Indonesia
    , came into two periods. One, directly from Africa, and two, from Indochina.
     
  14. Jun 23, 2016 #13

    Chronos

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    I think ice ages over the past couple million or so years probably played a factor. The rapid environmental changes wreaked havoc on many mammal populations during that time. Our dumber ancestors numbers probably declined in concert.
     
  15. Jun 23, 2016 #14
    Might be dumb, but much smarter than lions or elephants I think. I watched in discovery channel, even chimpanzee can use/make very simple tools.
    [A stick to be precise]
     
  16. Jun 23, 2016 #15

    Chronos

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    Think adaptability, humans unable to anticipate the advantages of secure shelters, clothing and food resources were at a disadvantange to those that did. It appears highly probable socialization was also a key survival ingredient. Organized groups of people can plan and execute survival tasks far more efficiently than unstructured groups of individuals.
     
  17. Jun 23, 2016 #16
    Of course! That's very logical. I didn't think of that. So, modern human being without tools can't survive in northern part of Greenland?
     
  18. Jun 23, 2016 #17

    Chronos

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    Not necessarily. Native indians inhabited greenland long before the first known nordic settlements were established around 1000AD; and survived long after the Norse settlements disappeared around the 15th century. The vikings rejection of native survival strategies is believed to have played an important role in the eventual collapse of their population. See https://www.lakeheadu.ca/sites/defa...tal_2007_ArcAnth_NorseGreenlandSettlement.pdf for discussion. Not that the native Dorset fared much better than the Norse. They too pretty much disappeared around the time of the little ice age, but, were almost immediately replaced by the Thule, who remain there to this day. Considering native tools consisted largely of what could be foraged from the environment tends to refute the proposition that modern humans could not survive in Greenland without tools. The Thule, in particulare, were well adapted to survive the varying environmental challenges presented by Greenland. The vikings, on the other hand, clung to their own cultural traditions, hence, were less well adapted to survive climactic upheaval.
     
  19. Jun 24, 2016 #18

    jim mcnamara

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    This is precisely explained by E O Wilson 'The Social Conquest of Earth'
    The concept is that social (group) behaviors, un-surpisingly, are subject to Natural Selection.
    His primary examples are ants and humans.

    FWIW - @Chronos I don't buy the 'dumber' comment - the idea anyway. Extinct human populations in Northern Europe had significantly larger brain size than modern humans. The assumption here, of course:
    larger brains are inherently more intelligent.
    https://en.wikipedia.org/wiki/Cro-Magnon
     
    Last edited: Jun 24, 2016
  20. Jun 24, 2016 #19
    Just want to add something to the discussion.
    Long time ago (30 years?), I have a book "Early Man" - Francis Clark Howell. Frankly I have forgotten his exact word. The book is in the attic.
    He wrote "Scientists (people?) were so ashamed that we are the descendants of Neanderthal, so when scientists found the remnants of a "new species", - Cro Magnon - they were very grateful if not delighted, so scientists gave every positive characteristic to Cro Magnon"
    This is the book, I have to look it up from google
    Early man.jpg
    I even forgot what the author name is, so I look it up from Google. The cover matches exactly as I remember it.
     
  21. Jun 24, 2016 #20

    Chronos

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    Bigger = brighter = more fit = unsupported by facts in evidence. A variety of lesser endowed critters have survived events which overmatched their larger brained contemporaries.
     
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