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1.8 Million-Year-Old Skull Suggests Three Early Human Species Were One
ananyo writes "A 1.8 million-year-old human skull dramatically simplifies the textbook story of human evolution, suggesting what were thought to be three distinct species of early human (Homo habilis, Homo rudolfensis and Homo erectus) was just one. 'Skull 5', along with four other skulls from the same excavation site at Dmanisi, Georgia, also shows that early humans were as physically diverse as we are today (paper abstract)."
What! Science says that there were three different species of humans, now it says that there was only one. See. Scientists keep changing their mind. How could you put your faith in them? Put your faith in Jesus, God and read the bible instead. The truth in bible doesn't change over time, unlike science. Creationism triumphs over evolution once again.
It is not exactly like that. It is rather that any given sample along one line, regardless where it is on the timeline, belongs to only one and the same species, regardless of evolutionary change! A new species is _only_ formed when one line is split into two lines. And even more surprising, to many, then is that neither is the same species as their ancestor, for solely technical reasons.
You are correct, I think I should have clarified by saying that the point on the timeline where a new species is formed is entirely arbitrary, and an individual at that point is wholly compatible with some number of generations to either side.
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Man, the real story here is the skull.
It dont really care what it suggests, the mere fact it was talking is creepy...
The true definition of species is a group that can and do inter-breed to make offspring. So, the line actually *IS* very clear cut... as soon as a mutation occurs that branches one set so they can no longer reproduce with the other, it is a new species. The problem is, determining that point in history using only archeology is very difficult and full of guesswork. Even if you have the DNA from all 3 sides of the tree, we aren't adept enough yet to be able to look at two pieces of DNA and say "yes these two could reproduce and make viable offspring", vs. "yes these two could reproduce but their offspring would all be sterile". That is when you form a new species.
That's pretty much the problem for the whole field. There are so few complete specimens (we're talking dozens, rather than hundreds) and they're generally so diverse geographically and chronologically that is becomes very difficult to say whether something was "species wide" or just individual variance. So you find a 4 foot tall skeleton on an island and you might be tempted to say "I've found a new miniature-species of human!", conveniently forgetting the fact that you only have one skeleton and dwarfism is a relatively common feature of the only human population we have a good sample of (modern us). That skeleton could have been the only 4 foot tall adult within a 100 mile and 100 year radius, and yet there's no way of telling unless you can find more specimens that agree or disagree. And those specimens may simply not exist to be found.
I've always found fields like archaeology & palaeontology particularly fascinating for this reason. It's one of the few areas of science where there will be some things that simply CANNOT be known, because no evidence has survived of it and we can't ever study the past directly. It is one of the only areas of modern study where there is a real sense of mystery that will never and can never be lifted. Every little discovery we make is like finding a single piece of a 100 million piece jigsaw- you learn something, but the balance of things not known is still colossal.
A new species is _only_ formed when one line is split into two lines.
Yes, but pinpointing the "split", is quite a problem. You don't need fossils to show this 'problem', it can be seen in what are known as "ring species" that are alive today.
Basically one species spreads both directions along a circular geological boundary. Despite the fact that all individuals along the expanding route can breed with the different races on either side of them, when the two expanding ends of the population meet at the other side of the boundary, they have become distinct species that can no longer interbreed. There is no point along the genetic line where the species forked, yet fork they did since each "end" of the route is a different species.
Another more linear example (like the fossil record) are the changes that occur as a species expands it's range up a tall mountain, there's a continuum of slight genetic variations from the species at the bottom of the mountain to the (different) species at the top. Again, there is no point on the genetic continuum where it can be said the species "split".
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
We like to think that it's clear-cut. When it's not, we quibble over just how to redefine "clear-cut".
http://en.wikipedia.org/wiki/Mule#Fertility
It seems we may be at the very tail end of Horse/Donkey differentiation.
(Yes this is an assumption on my part, but I doubt there's good reason to think otherwise. A case to demonstrate this for more than two generations is probably too statistically unlikely to ask for. It might conceivably be possible to get Donkey genes into the Horse population with a couple of really lucky generations. IANAG)
I won't join Slashcott. OTOH, If Beta goes live, I just won't be back until it's fixed. Sorry Dice.
God's own son wasn't especially white. The Bible makes it clear that he looked like a typical Galilean Jew; otherwise, he would have found it a lot harder to mix with crowds.
I never knew before reading Slashdot how many "tech nerds" really hate science.
I wonder how many of them are angry because they couldn't cut it.
You are welcome on my lawn.
5 skulls leading to pronouncements on the species and its evolution?!
5 of several tens or hundreds of thousands is not statistically significant.
This is why creationism can survive, because it at times makes as much sense as the extraordinary extrapolations tossed out by scientists.
Make it right. Demand that the scientists also share possible margins of error (in this case HUGE).
"Consensus" in science is _always_ a political construct.
I think they look at the complete picture and make their best guess based on all the evidence that they have and the best models that they have. The species concept is also inherently fuzzy. I'm not a biologist, but I've been told it can be fairly hard to tell if two living organisms are of the same species or not. Obviously, we should not expect perfect certainty about individuals that died 2 million years ago.
Scientists never really know anything, because knowing something with full certainty is an absurd idea. When it comes to the distant past our best hope is to be able to paint a rough picture. Of course, advances in chemistry and physics may make it possible to analyze fossils at the molecular and atomic level and find out all sorts of amazing things about them that were previously thought impossible, but even then the whole detailed picture will always elude science.
Creationists love this, but the problem with biblical creationism and Islamic creationism is that if there was a global flood 4000 years ago there would still be a global flood today, because there is nowhere for the water to go. Also, the moon missions would have crashed into the firmament that holds the flood gates to the waters beyond when they orbited the moon since the moon is attached to the firmament. It's funny that there are grown men that hold on to early iron age beliefs about the cosmos...
Put on some Speed Stick and you wouldn't be so awful.
I'm just delighted to be able to explain the ridge brow, knuckle draggers I've had to cover for all my life.
Of course these species are one. Still are! As are Homerus Erectus,(average hominids) Gluteus Rex,(species attracted to elected office) Rattus Habilis,(law enforcement and judicial hairy lizards) various mamosauruses (double breasted rod suckers) and ptero shrews( pinchy face complainers).
I can't get down the street for herds of them making nuisances of themselves all day long. We need a hunting season...
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!