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Humans Evolved From a Single Origin In Africa
Invisible Pink Unicorn writes "Researchers at the University of Cambridge have combined studies of global human genetic variations with skull measurements worldwide to show conclusively the validity of the single origin hypothesis. The alternative hypothesis contended that different populations independently evolved from Homo erectus to Home sapiens in different areas. The lead researcher explains, 'The origin of anatomically modern humans has been the focus of much heated debate. Our genetic research shows the further modern humans have migrated from Africa, the more genetic diversity has been lost within a population. However, some have used skull data to argue that modern humans originated in multiple spots around the world. We have combined our genetic data with new measurements of a large sample of skulls to show definitively that modern humans originated from a single area in Sub-saharan Africa.' The article abstract is available from Nature."
It looks like this research is already being torn to pieces:
"John Hawks of the University of Wisconsin-Madison says the paper is mistaken. A major flaw is that the current research is largely based on skull variability. "You can't find the origin of people by measuring the variability of their skulls," Hawks said.
"Differences in skull features are related to genetics, and genetic variation depends on how much mixing occurs with other populations. "The main problem with the paper is that it takes some assumptions from genetics papers of 10 to 15 years ago that we now know are wrong," Hawks said.
"Other scenarios, besides the single-origin theory, could account for the link between distance and skull variability. "Africa is ecologically diverse, and cranial variation is a function of environments," he said. In environments supporting hardy foods such as roots, people would need bigger jaw muscles, and thus larger areas for muscle attachments.
"Also, correcting for climate is not a good idea, according to Hawks. "The most important feature that is related to climate is skull size. So by correcting for climate, they are subtracting a major component of variability," he said.
"In his own research, Hawks is finding that natural selection has led to changes in thousands of genes during only the past few thousand years.
"I'm really thinking just the opposite of this paper," Hawks said. "There are differences in the skull between populations, including their variability, but it is mostly due to very recent effects and not the origin of modern humans."
"At the end of the day, a resolution to the "Out of Africa" debate may be impossible, he said. Most of the evidence can be interpreted as supporting both human-origins theories. "It's really hard to find observations that distinguish the two," Hawks said.
"The multiregional idea is identical to the recent African origin idea, except for its prediction that Europeans and Asians were part of the single population of origin and didn't become extinct."
There, fixed it for you.
The days of the digital watch are numbered.
A bit off-topic, I know, but what often puzzles me is that all living things basically work with the same chemistry. All have DNA, and there are many proteins that are physically very similar between different species, even between animals and plants. This leads me to conclude that all life must have come form one ancestor that materialized somewhere on the planet. But the earth is a big place. To me it seems very unlikely that life hasn't occurred in more than one place and more than one time. So how is it possible that all life, on a chemical level, is more or less the same?
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This evidence proves conclusively without a doubt that there is a 100% chance that humans either evolved from primates, were created by God, or both. Case closed!
I'm pretty sure these sort of ideas are thought up just to piss off creationists: "Hey guess what, we've found scientific evidence that the human race actually could have started from a single couple like Adam and Eve, but guess what? They were black".
I think it's highly believable that they traded various recipes for rolls, pastries, and other breads.
I just can't talk to you when you're right here.
I am not a scientist, nor do I play one on TV. But my understanding of the way evolution worked is that you need a breeding population sharing common mutations and traits in order to lock in evolutionary traits. The old textbook example for regular speciation within a main population a fertile jungle valley split in two by a great river. Species A was once on both sides of the river and populations could interbreed if presented the opportunity. But given enough isolation, and especially if any environmental factors differ on one side or the other, a Species B can emerge. When the changes are minor, one could refer to the changed one as a sub-species. If the changes become very pronounced, such that interbreeding is difficult or rarely results in viable offspring, then you could say that second population constitutes a new species.
Given that two identical populations can drift away from the ability to interbreed through nothing more than isolation, how likely would it be that one species, scattered across many environments, could independently evolve into a new species whose members could interbreed? That seems a bit off!
I do think that hybrid species are pretty cool, even though they don't occur too often in nature. We had the polar/kodiak hybrid shot a year or so back. Zoos also have many examples of lygers, tylons, etc. Wolves and domestic dogs can interbreed, the same goes with cyotes and jackals as well. It does make one wonder how far humans could drift apart if several populations were isolated for 20,000 years. I wonder if they'd all still look alike except for different bumpy foreheads?
Kwisatz Haderach
Sell the spice to CHOAM
This Mahdi took Shaddam's Throne
Adam and Eve were black? Next you'll be telling us that Jesus was Jewish!
Seriously, though, the creationists I respect go to the Bible/Koran/Talmud and say "God created the heavens and the earth" then go to a science textbook to figure out how he did it.
You are reading a copy of my copyrighted post.
Good points. I'm an evolutionist, and I find it sad that you are unlikely to be modded up on this. (Against the group-think and all that.)
When I read the article, the first thing I thought was 'I thought we could all agree on this?' That's the 1 big (important) thing the ID and Evo people agree on: We came from a single source.
Of course, I still haven't ruled out that possibility that evolution is controlled by God. It kind of muddies things a bit.
"If you make people think they're thinking, they'll love you; But if you really make them think, they'll hate you." - DM
I remember hearing that it's been proven genetically that there is one common male ancestor and one common female ancestor for humans. the problem was, they were about 100,000 years apart.
It was on television, so no reference.
Rational thought is the only true freedom
... we were in part genetically influenced by what we call alien life. Not in just one place on this planet.
Perhaps the real questions are regarding time lines and why evidence either exist or does not. Rate of deterioration under what conditions?
This whole Darwin vs. god vs. intelligent design is all rather silly.
Its like right to life vs. freedom of choice. Want to know the truth about that? Ask a starving child!
Likewise, the evolution of conscious beings is probably a mix of Darwin, god (the right conditions existing - father physics and mother nature) and intelligent design, even though intelligence can sometimes be stupid (selective breading and external intelligence influence)
Anyone who wants to divide what actually is, is looking to create a problem that doesn't really exist.
Yes, and that ancestor is a very simple RNA-based bacterium. And this evolved into DNA-based simple bacteria. Then bacteria which included other simple and ultra-specialized bacteria (cloroplasts and mitochondria). Which evolved into simple multi-celular life forms like sponges and extremely simple worms (hardly more than essentially an elongated torus whose surface was a bacterial film.) Which further evolved into more and more complex stuff.
And some figured out how to eat the others. E.g., fungi evolved to take another cell apart for food. And then some of those managed to, well, more or less do agriculture with other bacteria: the lichen are more or less a combination of a fungus and a bacteria, where the fungus traps the bacteria and helps fixate water and minerals for it, then scoop the food the bacteria produced. Or sometimes just destroy and eat those bacteria for food.
So there you already see the early split between plants and animals: one branch of the fork relied on photosynthesis to produce its own food and energy, using solar energy for it, and the other branch of the fork evolved to be basically parasites on the first one. Whether literally parasites eating the live plants (mostly plankton and algae at that point), or eating the corpses.
But before that fork, they evolved from the same ancestor, hence why they're still similar inside.
And from there it was often a race between species, driven by natural selection. E.g., the lignin based plants of the carboniferous era had a major temporary advantage, in that bacteria and fungi didn't yet exist which could digest this adaptation. However, that also applied to dead plants, which is why there's so much coal left from that age (and gave the age its name.) There simply was noone around which could eat a dead plant. But then bacteria evolved that could take apart lignin and celulosis. And then some animals evolved compartmented stomachs where they could store such bacteria so they could eat plants. (Don't think just literally animals. Some insects, e.g., termites, do exactly the same.)
And so on, an so forth, branching wildly ever since, and punctuated by some extinctions that trimmed the tree.
But, yes, once you trace all the branches back, it all leads to that first primitive bacterium. That's why it's all so similar at a chemistry level. Each step was a tweak of what already existed. Each step evolved more complex proteins, or just different proteins, and more specialized roles, but it was still based on the same reactions that worked before.
E.g., it still had enzymes which copied a strand of RNA, between a "START" and an "END" marker, to a protein. Even in DNA based cells, it's still not that horribly different: there's just an extra step of transcribing the DNA to RNA, so then you can transcribe the RNA to a protein. (As to why that more complicated mechanism evolved by natural selection: because breaking a single strand of DNA, for example by radiation or some chemicals, can still be fixed, while the same break in RNA means cell death. So the DNA based mutants were hideously more survivable than their RNA based ancestors.) Anyway, we essentially we still use the same mechanism of producing the proteins as that original proto-bacterium ancestor.
Where did that original bacterium come from? Well, probably from something even simpler. A bacterium is nothing more than a drop of sea water with a membrane. It makes it easier to keep the contents isolated from the rest of the world, much like a test tube does. But ultimately you just have some reactions in liquid water inside. So probably some chemica
A polar bear is a cartesian bear after a coordinate transform.
Scientists, as you point out, often have a 'religious' view of certain theories. We saw it back when the Big Bang theory was first proposed; the scientists of the day saw it as 'thinly veiled creationism'. What drives science forward, though, is when you have two groups of fanatics screaming at each other, the non-fanatics generally cluster to the side with the better arguments and better evidence. That's why the Big Bang theory is now taught in schools, and the various steady state theories are discarded, as are most of the 'Big Crunch' ideas.
Anyway, as far as your 4 theories go:
1. The Universe came into existence completely from nothing, by itself. There was nothing, then everything over time. Start with nothing & work forward.
I believe that Hawkings is actually espousing this idea. It seems highly unlikely to me, since it violates the First Law of Thermodynamics, without which all Chemistry, Physics, and Biology is meaningless.
2. The Universe always existed
Seems highly unlikely, given that a) the universe is expanding with no sign of collapsing and b) the Second Law of Thermodynamics.
3. The Universe is an illusion
Possible, but a pointless theory. Even if true, the universe behind the illusion still has to follow one of the other 3 possibilities (but #1 and #2 might be possible in a universe with different laws)
4. The Universe was created.
Almost certainly the case, the question is just by what. Perhaps another universe is unaffected by the Second and/or First law of Thermodynamics, and our universe was created there as an experiment/toy/prop. Perhaps our Universe was born from a black hole in another universe- and the black holes in our universe are also creating more universes. God creating this universe seems at least as likely as anything else, but that merely tells us he's insanely smart and/or powerful. He may care about our universe, but not care about us.
Our best science tells us that we can't know how the universe was created. Unless we get the opportunity to witness another Big Bang or talk to God, it seems likely we will never even have that good of an idea.
You are reading a copy of my copyrighted post.