Teeth are the strongest things inside the human body, so it’s not at all surprising that the most common fossils are dentures. They’re also among the most useful for paleontologists and archaeologists since these speak of how our ancestors lived, what they ate or, most importantly, what species they belonged too. Alistair Evans of Monash University in Australia took a refreshing look at hominid teeth evolution. He found human evolution was much simpler than previously thought, but also that wisdom teeth considerably shrank around the time complex tools began to be used.

The  hominin tooth shown in white could predict the size of the other in line. Image: ALISTAIR EVANS,

The hominin tooth shown in white could predict the size of the other in line. Image: ALISTAIR EVANS,

Evans and colleagues based their work on previous experiments with mice whose results suggest that the size of a tooth influences the size of those adjacent to it. This is called the “inhibitory cascade model”, and Evans says this applies to hominins as well.

Thousands of teeth fossils were analyzed, belonging to either hominins or modern humans. Based on this catalog, the team split the teeth into two groups: the genus Homo (that’s us, along with other close relatives like Neanderthals or Homo Erectus) and non-Homo hominins like  australopiths (remember Lucy?) which are the first primates to walk on two legs.

Human wisdom teeth, the ones farthest in the back, are small or in some cases don’t even develop. But as we move down the time axis, these are far larger. Early hominids had the chewing surface of wisdom teeth up to four times bigger. Around 100,000 years ago, or when tool use and cooking became wide spread, these shrank considerably since our ancestors could use a flint instead of teeth to open nuts or crest meat.

“It’s always been presumed that sometime in early Homo, we started using more advanced tools,” Evans said in a press release “Tool use meant we didn’t need as big teeth and jaws as earlier hominins. This may then have increased evolutionary pressure to spend less energy developing teeth, making our teeth smaller.”

Interestingly, if the teeth of an australopith were large in the back, the rest in front were also. For the genus Homo, the same proportions were seen, only the teeth were small confirming the inhibitory cascade model, the researchers report.

The implications are pretty huge. It means that scientists now reliably reconstruct the teeth of early hominins even if they only have one single tooth at their disposal. It also means that we now have a reliable classification tool. Homo naledi, recently unearthed in South Africa, for instance has a mix of traits with some resembling Homo, while others more akin to australopith. By studying the teeth of H. naledi, it’s possible to have a firmer grasp of where this hominid sits in the family tree.

 

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20 Comments

  1. 1

    Evolution is just a mythical Unicorn ,Evolution even lowers the human intelligence below that of all the monkeys and the Apes communities.
    Medical biology which is real science has delivered wonders to humanity. But What did Evolution biology deliver besides false ideologies based on lies and totally inaccurate data. ?
    Millions of years ago the dinosaurs were all destroyed by divine intervention,and not by a meteor as evolution biologists predict . In Short… The old creation, excluding the planet, and the ocean was created by the Super being Lucifer .The dinosaurs were created by Lucifer and not God. God destroyed Lucifer creation after Lucifer rebelled and his name was changed to Satan.
    Million of years after the real star wars took place between Lucifer angels and God’s angles , God renewed the planet with his own creation which we all can see is far more diverse and far more superior than Lucifer creation ever was.
    There is no connection with the old creation, and the new creation there is no missing link .
    It is very easy to see that both creations were created by two totally different God’s.
    I’ve also spent a lot of time trying to make some sense about evolution, but nothing stacked up, and nothing made any sense . So I then began to try and search were the facts really are and not where I wanted the facts to be.

  2. 2

    It’s interesting that every time there’s an article on evolution (and evolution of humans seems to particularly offend religious nuts), someone will post comments that are totally imaginary (i.e. devoid of facts). Science is self-checking. Scientific opinions are always subject to revision as more facts come to light. The theory of evolution has been well established for some time now, and supported by many, many FACTS. That’s what a theory is after all, not merely someone’s unsupported opinion.

  3. 3

    In my church going experience there is a fine line between extreme faith and mental illness. I have seen people cross over several times.

  4. 4

    Maybe it’s simply because religious people also get offended by Evolution. Especially when religious people are repeatedly being compared with monkeys by Evolution nuts.

  5. 5

    You people talk about science, yet you don’t have a clue what real science is creation is all about science .Here is just one example. Man and Woman have sex, sperm from man makes contact with woman egg ,and presto life begins to form. So then, where do the monkeys fit in,among the scientific creation of a baby?
    Human science can only discover What God has already created by his own science . So If human scientists think that they are so great, then they need to create something themselves that doesn’t already exist, in which case God will have to discover instead of them.
    Having said that There is good science medical biology is very good science .But evolution biology is nothing but crap.

  6. 6

    the name “bongorocks” rather says it all! I used to be a devout christian or believer in a supreme being BUT I was not affraid to question religion 10 years ago and the more I read, the more I could not believe I could have been SO blind as to not see how utterly rediculous believing in a higher being was…science is discovering more and more of our evolutionary past and it really does make sense.

  7. 7

    I love your reply! How true….none more than people saying they “heard a voice telling them xxxxx”. This is exactly what mental people describe as ” hearing voices in their head”…. The believers think these voices are God inspired, the doctors think it is a disturbance of the brain. I agree with the doctors….

  8. 8

    How can anybody prove that people who claim to hear voices are mentally ill.? How can they prove that they are not in fact hearing voices just like they claim they are?
    I believe that the once who are in fact mentally ill are the same people who say that those people who claim to hear voices are mentally ill.
    In the new testament, Jesus cured the sick ,made the lame walk, made the blind see , he even raised the dead ,But when it came to what they call today mental illness, Jesus cured those people by ordering the demons to come out . At one stage the demons came out and entered into a herd of pigs which cause the herd off pigs to panic as they stampeded over a cliff and fell down into the sea below and all got drowned. Many people who are described as mentally ill also attempt to commit suicide, and unfortunately many succeed just like the herd of pigs did.

  9. 9

    I could refer you to a host of books and articles which can scientifically explain very clearly about souls, ghosts, paranormal happenngs, people who have had an out of body experiences, looking down at themselves etc, etc and how the brain is comletely responsible for all these things……not a heavenly body. Remember, in the centuries past many people were killed for thinking the earth was flat, then the religious leaders were proven wrong. They have been proven wrong again about evolution…the world is more than 4800 years old….then there was the bit about the the earth rotating around the sun or is it the other way around…whatever the old way of thinking was it was proven incorrect and people were called heretics needlessly. If you are curious as I was many years ago, you will discover a whole lot more about the bible. I would suggest ALL of Lawernce Gardner’s books on the subject. He is an biblical historian and debunks all the myths…but you have to be willing to go out of your comfort zone and learn the facts. It was not easy for me but when I look back at what I used to take at face value on faith, I am ashamed I could have been so gullible.

  10. 10

    Hi there again…please open this link about souls etc. It makes complete sense!
    http://www.humantruth.info/souls.html
    Like the earth believed to have been flat long ago, we are only now with science and enquiring minds discovering the power of the mind…….

  11. 11

    I totally agree with you that souls and ghosts don’t exist .Those religions who teach they do are wrong and totally misleading . The bible refere to soul to our physical bodies, not to a soul that when we die it goes to hell, or heaven.In fact the bible also refers to animals as souls . The bible repeatedly says that when we’re dead we are dead, it doesn’t say anywhere that when we die we go to heaven to live with the Lord. But on the other hand the bible also reveals that ghosts are demons transforming themselves as the souls of the dead, to fool the people into believing that when we die we are not really dead.
    God told Adam and Eve personally , that they shall surely die .But later just like in cartoons, Satan spoke through a snake, and told them that they shall not surely die .Notice, that both God and Satan used the word ” SURELY “And Surely means surely. So the question is, which one of the two surely should we believe? Billions off religious people that believe that their soul goes to heaven when they die they are still believing the Satanic Surely and not the God Surely, Just like the first people did.In the meantime Satan is busy using his ghosts tricks impersonations to make sure that we continue to believe his surely that when we die we still alive, when in fact we are surely dead . Your statement saying that souls don’t exist is totally correct , but on the other hand the ghosts bits are totally and completely wrong. Another proven point that when we die we don’t have a soul which goes to heaven is Jesus death example ‘

    Jesus didn’t go strait to heaven when he died,Jesus only went to heaven after he was raised from the dead .
    The bible says that when we die our spirit goes to heaven The spirit is not a soul that goes on living after we die . The bible says that when a soul die.{ meaning physical bodies} the human spirit goes to God who gave it. but the spirit of the animals goes downwards. Jesus did say just seconds before he died, In your hands I commend my spirit.
    The spirit is what makes humans so intelligent .Our brain is designed with spirit intelligence .But all other creatures brain is designed with instinct intelligence ,neither spirit nor instinct can be detected by any scientific methods .Both invisible forces can only be detected by observing what humans are capable of creating and what animals are able to create compared to humans.
    The bible should be read and studied in two ways. One way is from a religious point of view, and the other is from a scientific point of view.Because the bible is not just about religion it’s a book given to humanity from another dimension. Personally I studied the bible both ways and as far as I’m concerned I’ve discovered that neither religions, or science have a clue what the bible is all about.
    Personally by reading and studying the bible with an open mind and free from all religions and scientific deceptions that’s how I believe that I have learned that the dinosaurs where created by Lucifer and not by a freak accident of evolution. But that’s another story .
    I’m not concerned about any religion, or science. I try and search for the facts where I think the facts may be and not where I want the facts to be.
    I believe in science like medical biology for example , but I don’t believe one little bit at all in evolution biology.

  12. 12

    Hi …it’s Quality that counts and not quantity .WE don’t need a whole hosts of books and articles .All we need is just one book only . There is only one book on this whole earth that reveals what ghosts ,spirits ,Angels and demons really are. Science cannot explain or understand the supernatural .

  13. 13

    So you jumped from the frying pan into the fire. I turned my back on every religion since I was 6 years old. But I didn’t go and join some scientific religion either. My previous comment explains what I think of both Christianity, and evolution biology, or any other religious organization.
    If you where ever a christian then at least you should have learned that every bit of creation has been scientifically designed { Not by human science ,Oh how they wish} but by God Science.
    With respect, and without being sarcastic like you are. I have to tell you that you have learned nothing. because if you cant see the science behind creation then you don’t have a clue what science is.
    How can you compare your little brain against the mind of God ?. And by the way, God is not some religious figure ,God is the boss off all aliens. The bible is full off aliens but not the aliens that your science is looking for. Those type of aliens don’t exist except on the X file show.

  14. 14
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  16. 16

    I wish to apologise. I should not have insulted your bongorocks name as I did. Suffice it to say, science is not a religion….religion is a faith based programme….science looks for factual answers to the unexplained…..it is fact based. It’s facts can be substantiated where as the Bible can be interpreted to suit the teller or believer……science has blown right out if the water many faith based presumptions….science does not hold all the answers but is always on the look out for the “why”…it never procrastinates to know it all…..it does not base its thoughts on “one book” which I presume rightly or wrongly you were referring to as the Bible?
    In any event, each to his own…..I am very glad I now rely on the facts and not the fiction….the fiction was very comforting though and was probably the hardest part for me to leave behind. Let us part as friends.

  17. 17

    No worries . It’s just that I’d rather get challenged with answers rather than Sarcasm.
    Just like you said, each to his own. But I didn’t need science to blow all faiths out of the water and that includes evolution.
    Evolution biology is a faith on it’s own. And the bible blew that faith out of the water as well.
    Also. Some Science especially the science in your are is also a religion Just ask Tom Cruise he’ll tell you.

  18. 18
  19. 19

    oh, please….Tom Cruise is a Christian Scientist…that does not mean he is a scientist…..I disagree evolution biology is a faith …evolution science is based on proven facts…..look at the various bits of the human body which through evolution have become redundant….the coxics (sp?) or what used to be a tail bone, the appendix, the eye teeth getting smaller as we do not need to tear our food…the further north one lives, the black skin became white so as to attract as much sun as possible to stay healthy…….look at horses and how their feet used to be toes……in fact their fifth toe is half way up their legs today and is called a chestnut if I remember correctly. There is a book called “The Fish Within Us” tracing how we evolved from fish…it is quite incredible looking at the drawings and what changed to what during evolution. They say that farmed salmon is evolving to such a degree it is almost a different species to wild salmon all because they have to live in comfined areas and are evolving to cope with their artificial surroumdings. No, I am afraid evolution is very much proven to be real. I do not find this to be threatening however…more fascinating than anything….. I believe that if there was a higher being, it would have made us perfect the first time instead of fiddling around with the pattern of all living creatures in a trial and error manner. I am not alone in thought on this.
    I hope I am giving you a less sarcastic answer and a more challenging one. Sometimes emails can be misread as being what they are not intended to sound like if one were actually talking.

  20. 20

    The paper fails to distinguish between causation & correlation. Postulating adult tooth mass/size of 3rd molar teeth available in archaeological record is a dependent variable of social development (advent of tool making societies) seems a bit of a stretch. Isn’t it just as likely that as alveolar crest & body of mandible length diminished & would only accommodate dimensionally homogeneous 3rd’s, those born with larger wisdom teeth developed pericornitis & cellulitis and died out early?
    While interesting that molar size decreased over time, conclusions presented seem speculative & flawed.

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