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Mr Caveman stayed close to home

2011-06-02 10:12

Paris - Scientists on Wednesday unveiled evidence that two species of early cavemen lived and died near their places of birth while most females of the same species settled down after coming from afar.

The study, published in Nature, offers an unprecedented glimpse into the social fabric of australopithecines, an extinct line related to humans that dwelt in southern Africa some two million years ago.

It also challenges the axiomatic idea that our distant forebears began to walk on two legs rather than four in order to cover great distances in search of food or shelter.

If males limited their wanderings to hunt-and-gather forays, then the shift to walking upright might have been driven by other needs, the findings suggest.

Up to now, very little was known of the lifestyle and kinship patterns of our two-legged ancestors.

Behavioural clues


"Disembodied skulls and teeth are notoriously poor communicators," quipped Matt Sponheimer, an anthropology professor at the University of Colorado at Boulder and a co-author of the study.

For the new study, scientists devised a method worthy of Sherlock Holmes to "make these old bones speak", Sponheimer said.

The behavioural clues were locked inside a handful of two-million-year-old teeth.

Tiny variations in the atoms of a heavy metal element called strontium correspond to various types of soil and rock, thus acting as a telltale of identifiable geographic locations.

Because strontium works its way into tooth enamel only during the first years of life, the element thus shows whether a primate grew up in the same place where she or he dwelt and died.

The scientists examined teeth from 19 individuals who lived 2.4 to 1.7 million years ago, eight Australopithecus africanus and 11 Paranthropus robustus.

Both species lived in woodland savannahs, probably subsisting on a mix of tree fruits, grass, seeds and nuts.

Lifestyle

Males and females in the sampling were differentiated on the basis of size.

Laser analysis of the strontium isotopes showed that only 10% of the males originated from outside a range of 30km2, compared to more than half of the females.

The males, in other words, probably strayed only rarely more than a few kilometres from their caves.

Their female partners, however, had often migrated from afar, even if they adopted the same close-to-home lifestyle once settled.

"Here we have the first direct glimpse of the geographic movements of early hominids, and it appears the females preferentially moved from their residential groups," said Sandi Copeland, also of the University of Colorado and lead author of the study.

The practice of females leaving the nest to join the family of their mates has been common in most human cultures across history. Chimpanzees and bonobos also follow the same pattern.

But most other primates, including gorillas, do the opposite: females stay with the group they are born to while males move elsewhere.

Problems

The discovery came as a surprise, and calls into question long-held views about how primates came to prefer moving on two feet rather than four, the researchers said.

"We assumed more of the hominids would be from non-local areas since it is generally thought the evolution of bipedalism was due in part to allow individuals to range longer distances," said Copeland.

"Such small home ranges could imply that bipedalism evolved for other reasons."

The study sheds new light on the "diet, group size, predator avoidance and home-range size" of what may be our direct ancestors, Margaret Schoeninger, a professor at the University of California at San Diego, wrote in a commentary, also in Nature.

But it also raises many vexing problems, she added: "How the australopithecines balanced predator avoidance and the need to compete for food remains an open question."

Comments
  • mbossenger - 2011-06-02 10:19

    How long before someone pops up and says the earth is only 6000 years old?

      NuttyZA - 2011-06-02 10:57

      I was wondering the same thing :)

      ManOTMoment - 2011-06-02 11:15

      Technically its 10 000 y/o

      NuttyZA - 2011-06-02 11:25

      ManOTMoment Technically 10 000 y/o BUT in reality +- 4.5 Billion

      mbossenger - 2011-06-02 11:28

      Technically closer to 4.5 billion year old.

      oxygen - 2011-06-02 11:57

      :)!ha!

  • stephen scott - 2011-06-02 10:54

    obviously, there were no taxi's back then.

  • Vlooi - 2011-06-02 11:20

    But on the other hand some of them drive taxis today.

      stephen scott - 2011-06-02 11:42

      nice one

  • Fredster69 - 2011-06-02 12:54

    You speculate that they lived 2.4 to 1.7 million years ago. That is a 0.7 million years difference. Close to 30% speculating... how correct are the "facts" ... Evolution is a religion.

      stephen scott - 2011-06-02 13:15

      how accurate is carbon dating? very inaccurate I guess, but at least there is science behind it, not just wishfull thinking

      Justin.A - 2011-06-02 13:19

      //You speculate that they lived 2.4 to 1.7 million years ago. That is a 0.7 million years difference. Close to 30% speculating how correct are the "facts"// Sorry your counter paper for peer review refuting these findings is where? Common descent is a fact, the only place there's a conflict is in your head.

      mbossenger - 2011-06-02 13:44

      Actually, on the scale of the age of the earth, it's 3 orders of magnitude (1000 times) smaller than the age of the earth, a very small margin of error. Why do you make the statement that evolution is a religion.

      NuttyZA - 2011-06-02 13:57

      Fredster, you obviously don't understand the things you read, no wonder you are confused... their IS no speculation... the article states that they examined teeth from 19 individuals, who lived 2.4 to 1.7 million years ago.... in other words, Individual 1 lived 2.4 million years ago, individual 2, 2.1 million years ago.... indvidual 19, 1.7 million years ago... Stephen Scott, they don't use carbon 14 dating to date fossils which are so old because carbon 14's half life is too short (about 5700 years)... for older fossils, they use Uranium-Lead or Potassium-Argon dating etc as well as stratigraphy...Uranium_lead dating has an error margin of about 2% to 5% so something dated back to 2.4 million years ago would be between 2.52 million and 2.28 million years...a 120 000 year inaccuracy at the most

  • GLY - 2011-06-02 13:55

    “The discovery came as a surprise, and calls into question long-held views about how primates came to prefer moving on two feet rather than four, the researchers said”. I wonder how long it will be before other “long held views” are called into question, like the age of the earth. There are no details where these remains were found. Tests were done in a 30Km 2 area and the fossils were obviously not found lying on the surface. Whilst tests were done on a 30Km2 area, how deep into the soil were the tests done. After 2 million years the surface level would have altered but do scientists know by how much? This raises more questions than it answers. ” probably subsisting on a mix of tree fruits, grass, seeds and nuts.”” The males, in other words, probably strayed only rarely more than a few kilometres from their caves”. Too many “probably”’s for scientific conclusions that I can accept.

      pieter.bosch - 2011-06-02 14:48

      @GLY: Any scientific backed ideas except these probables about their food, age and movement? Not likely so i would rather except these probabilities than your "not a clue"...Read the article or find out from the researchers about the locality of the samples and their age. The current surface level may not have to much to do with the age of the teeth as these were deposited in ancient caves, of which the age of the layers may be determined. Please read on the subject before you display your ignorance and waste peoples time to explain things to you.

      mbossenger - 2011-06-02 14:57

      I'm not sure of the relevence of your question as to how deep the test were done. Once again, we come back to the old misunderstandings about science - nothing is "proven" in science. Evidence is accumulated. And I'm confident the age of the earth is "probably" not going to be revised from 4.5 billion years to 10,000 years anytime soon.

      Justin.A - 2011-06-02 15:23

      //Too many “probably”’s for scientific conclusions that I can accept. // Well good thing you read the full paper from Nature then? No? Thanks for you opinion on an article then.

      GLY - 2011-06-02 15:35

      pieter, Why do you have to insult me. You have shown your misunderstanding of my question. I did not say that the layers of the earth had anything to do with the age of the teeth. I will try and clarify my question. Fossels are found either on the surface of the earth or buried say 2 meters 5 meters or even 10 meters below the current surface of the earth. If for example they were found at a depth of say 2 meters, then it may be safe to assume that their living area at that time was also 2 meters beloe the current surface. It is this depth that I am asking about. I gues that i trod on your toes, interesting that if you are unable to answer my questions then I guess that you have not reserched the matter either. One further question if you believe the theories you mentioned why would it be a waste of time for you to explain them. I recall my statistics lecurer saying that "everything is possible but not everything is probable". Still too many probables for me to accept. If you disagree please explain, if it is not too much trouble or perhaps you are angry because you do not have the answers.

      Ateis - 2011-06-02 16:00

      @GLY: A question - are you a christian?

      GLY - 2011-06-02 16:44

      @ateis Yes I am. Do you have the answer that I am looking for?

      Pedi22 - 2011-06-03 14:17

      do you suggest(considering your ability to estimated earth age with relation to fossilized layers) that in a long run of surface layers addition,will the earth meet the sky? if so why should i worry of inventing a better transport to heaven if in future people can be able visit God by feet( only if ever earth layers can meet the sky).

  • nandnz - 2011-06-02 16:47

    @GLY your statements discredits logic now when looking at scientific notions they are more probable yes but probable is more reliable than hope? these theoretical particulars take into account far more inherent elements which makes it more credible than any other alternative

      GLY - 2011-06-02 16:58

      @nandnz interested to know how much investigation have you done on the other alternatives?

      Justin.A - 2011-06-02 19:59

      @GLY There are o alternatives to evolution, of course I could be wrong, would love to see soome peer reviewed evidence. Like in the journal Nature for example

  • Pedi22 - 2011-06-03 14:04

    Is this a career advertisement,anyway at least science keeps homos discussing with little understanding and speculations and at last gives birth to facts after one generation has passed on, as those zillion or countless years fossiled primitive or should i say primates relatives.

  • Ru - 2011-06-03 15:25

    I was wondering what toothpaste this caveman used that his teeth could last 2milj years? If I could use it once maby my teeth would last me my lifetime.

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