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Gene MYH16: A Tasty New Jawbreaker

Posted by michael on from the chew-then-swallow dept.

kid_wonder writes "Jeremy Roenick take heart! Glass Joe take heart! Scientists discovered that humans owe their big brains to a single genetic mutation that weakened our jaw muscles about 2.4 million years ago. So I guess now we can call all those dopey muscle bound guys 'apes' with a clear conscience."

10 of 71 comments (clear)

  1. "Discovered"? by afabbro · · Score: 4, Insightful

    "Discussed a new theory" is more accurate...

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    1. Re:"Discovered"? by bugnuts · · Score: 3, Insightful

      Stop calling everything "theories" as if that word weakens the probability of it being true. That is the same lame tactic used by Creationists.

      Theories are developed hypotheses, that have withstood scientific examination. Some theories are stronger than others, such as evolution, which has extremely compelling and a wealth of strong evidence. Examining genes and doing the statistics on them is also extremely compelling. Everything you do with technology including the computer you're using now is supported completely by theories. Does that mean it's not true? Kind of like disproving Zeno's Paradox -- please stand in front of the arrow.

      So, sure, it's a theory as opposed to a proof. But you can probably bet your life on it.

    2. Re:"Discovered"? by Ayaress · · Score: 4, Insightful

      I'm pretty sure I've posted this exact reply to the exact parent a dozen times over.

      In science, Theory is the highest level of understanding. Law and observation are, in fact, much lower on the heirarchy.

      Observation is dumb: It's just what you see. "Oh, the sky is blue." "It hurts when I hit myself with this rock." "Look, there's another rat." That's observation.

      Law is also pretty dumb. It's just a set of rules derived from observation. e=mc^2 fits observation, and it has some interesting connotations, but it doesn't say anything about WHY the equation works, and it says even less about HOW matter and energy are interchangeable.

      Theory is an overarching collections of observations, laws derived from observation, and principles deduced from laws.

      Theory explains why laws work, and why observations are as they are.

      To be granted the distinction of 'theory' an idea must:
      1. Explain any and all laws and observations already explained by a previous theory (example: to be valid, Relativity had to encompas Newtonian mechanics);
      2. Explain such in an imperical manner (any forces involved must be identified and observed. This is why there is no theory regarding dark energy and dark matter - they have yet to be identified, observed, or quantified);
      3.a. Explain something not covered in the existing theory (Darwin's theory explained why rats with their tails cut off did not have tailless offspring, as Lamarck's theory said they shoudl);
      OR
      3.b. Explain the existing theory in simpler terms (such as the replacement of phlogiston theory and epicycle theory by their more advanced, but much simpler, successors).

      Now, by calling an observation a Theory, you are, in your misguided attempt to discredit it, in fact exaulting it to a much higher status than it claims to hold already.

    3. Re:"Discovered"? by Smidge204 · · Score: 2, Insightful

      I think the parent was commenting on how many people disregard ideas that are not compatible with their views (eg: Creation and Evolution) by saying "it's just a theory".

      A "theory" is usually given much more weight than a "belief", because theories are typically based on observation and experimentation, reviewed by peers, and have been used to make accurate, testable and verifiable predictions. Beliefs tend to be more based on emotion and hearsay. It is therefore reasonable to assume that a "theory" is closer to reality than a belief, if only in a practical sense.

      Moreover, theories are seldom touted as absolute facts, and most credible scientists will admit their theory wrong/flawed when given sufficient evidence.
      =Smidge=

    4. Re:"Discovered"? by b-baggins · · Score: 2, Insightful

      This isn't even a theory. It's a hypothesis. It requires experimental verification before you can call it a theory.

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    5. Re:"Discovered"? by RevAaron · · Score: 3, Insightful

      Indeed. I hate it when people say this or that (usually "evolutionism"; -ism, heh) is "just" a theory. A theory is a big deal. Perhaps creationism is "just" an educated guess, but the definition of the word theory is not. In common usage, people use the word "theory" to mean just that- an educated guess, rather than a hypothesis backed up by a lot of evidence.

      And no, like you say, it's not a proof- but proofs really only exist in the world of mathematics. No scientist can say that a particular theory is 100% proven, ever. That is science, and the fact that science can adapt and grow with new information is one of its great strengths.

      *sigh*

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    6. Re:"Discovered"? by bugnuts · · Score: 2, Insightful

      This theory could be true, or it could equally not be true.

      Wrong. Simply because there are two choices between true/not-true, does not give it 50% chance of either.

      There are theories you bet your life on, every day. If they all had an equal chance of being true or false, you would be dead now. Try flipping a fair coin 100 times and getting all heads. Is there a chance you can do it? Yes, but is it likely? No.

      He calls it a theory rightly, and it does weaken the probability of it being true.

      You know nothing about probability. He could call it a yellow elephant with handlebars, but that doesn't affect the probability of it being true or not. But he would want you to believe that.

      It is a theory, rightly, but he does not call it a theory rightly. He calls it a theory as if that somehow makes it less likely to be true. They're all theories and all scientists know this, but he was simply using misleading rhetoric and calling it a theory wrongly.

  2. Uncertain cause and effect by Chilltowner · · Score: 4, Insightful

    While it's true that Australopithecus species had much smaller brains than anatomically modern humans and other of the Homo genus, this isn't the gene that separates us from the apes--earlier species made that division.

    It also seems to me that they may be putting the cart before the horse here. Depending on the feeding habits of our Homo genus ancestors, a smaller jaw could be a decidedly large disadvantage, limiting the kinds of foods that could be eaten by a scavenger species such as our ancestors. It seems possible, and even likely, in this case, that our already advanced brains provided a large enough offset against the loss of powerful jaw muscles. This might mean that we were well on our way toward advanced thinking before the loss of muscle mass in the jaw.

    Anatomical structures always pretty tricky, especially when it comes to judging cognitive development and other tangential related adaptations. The kinds of mutations that make us human (smaller jaws, larger heads, versatile voiceboxes) also tend to cause of a lot of potential problems (restricted diet, difficult birth, tendency to choke). Weighing the value of one change over another become enormously difficult.

    Not to knock their work, though--this is pretty amazing stuff and will definitely be another piece of the puzzle for anthropologists to consider. My only concerns are that we not look at this as a) the great divide between us and the other apes or b) the silver bullet that made us the brainy folks we are today.

  3. Re:Don't buy into the hype by Ayaress · · Score: 3, Insightful

    Yes, but this comes down to the constant issue with any scientific literiture. There are several versions of every story:

    1. What the scientists actually think (what I was addressing in my post).
    2. What they tell the people they get their grant money from (to make it sound more profitable)
    3. What the damned journalists say when they get ahold of it.

    For example, take last week's discovery of sediments on Mars precipitated from salt water:

    1. What NASA thinks: "Well, there's the proof of the sea we were looking for. Pity it's not there anymore"
    2. What NASA says: "Hey look at this, there used to be water on Mars! And water doesn't just disappear, you know. Imagine what could be done with that much water!"
    3. What the journalists say: "OMG OMG OMG TEHER WERE LIFE ON MARZ OMFG!!!111oneone"

  4. Apes by AllenChristopher · · Score: 2, Insightful
    "The conclusion that this mutation was responsible for the divergence of humans and apes is just plain wrong."

    It's just plain wrong in another way. Humans are both apes and primates. The divergence is rather far down the taxonomic tree. We and our proto-human relatives are in sub-family Homininae, as distinct from the other members of Hominidae. The Hylobatidae are also apes.