News1 min ago
Missing link
26 Answers
<----- This is a representation of "Ardi" Ardipithecus Ramidus, reconstructed from fossil fragments and possibly the earliest Hominid.
Thought to have lived 4.4Ma ago and pre-dates "Lucy" Australopithecus by about 500Ka.
Some say Ardi may well be Lucy's direct ancestor and as such would indeed be the missing link but there seems to be some contention.
I've read a fair bit but to be honest it's a lot to take in.
I was wondering if anyone could shed some light on this in simple terms, preferably without providing links that link to links that lead back to square 1.
Has any recognised scientific body come up with a definitive answer?
Thought to have lived 4.4Ma ago and pre-dates "Lucy" Australopithecus by about 500Ka.
Some say Ardi may well be Lucy's direct ancestor and as such would indeed be the missing link but there seems to be some contention.
I've read a fair bit but to be honest it's a lot to take in.
I was wondering if anyone could shed some light on this in simple terms, preferably without providing links that link to links that lead back to square 1.
Has any recognised scientific body come up with a definitive answer?
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Firstly, the term "missing link" is horrible and not really used by scientists. Evolution is a continuum, a gradual change from one thing into another over a long period of time. Think of it as analogous to looking at a rainbow and how red gradually becomes violet. Sure, you can point at a place on the bow and say, "that's yellow" but you can't easily point out where orange stops and yellow begins. Species is like saying 'yellow'; you can clearly tell it's different from another one, but there was lots of small iterative changes to get there.
The really short answer is to note that unless you can extract some DNA, the best possible case for any given specimen of fossil is that you can observe some features that are present in later species but not proposed earlier species, and some that are found in proposed earlier species but not the later species. This would demonstrate that there existed a species from a given time period that showed the features one would predict to see if evolution were correct. If you found one which lacked key features that existed in both the earlier and later specimen, you could reasonably assume what you have could not be an ancestor of the later species.
What you cannot prove is that your specimen is definitely decended from the earlier species or that it definitely gave rise to the later species; you are simply showing that a species of the sort that ought to exist if evolution is true did in fact exist.
The really short answer is to note that unless you can extract some DNA, the best possible case for any given specimen of fossil is that you can observe some features that are present in later species but not proposed earlier species, and some that are found in proposed earlier species but not the later species. This would demonstrate that there existed a species from a given time period that showed the features one would predict to see if evolution were correct. If you found one which lacked key features that existed in both the earlier and later specimen, you could reasonably assume what you have could not be an ancestor of the later species.
What you cannot prove is that your specimen is definitely decended from the earlier species or that it definitely gave rise to the later species; you are simply showing that a species of the sort that ought to exist if evolution is true did in fact exist.
Thanks for your answers.
chakka35,
Homo ergater and Homo habilis are both thought to have shared a common ancestor, a species as yet unknown,a missing link perhaps to Australopithecus.
Ardipithecus is thought by some to be the ancestor of Australopithecus, another missing link, in as much as (to my understanding) the jury's still out.
My question rephrased then:
Is it yet accepted that Ardi was Lucy's direct ancestor?
chakka35,
Homo ergater and Homo habilis are both thought to have shared a common ancestor, a species as yet unknown,a missing link perhaps to Australopithecus.
Ardipithecus is thought by some to be the ancestor of Australopithecus, another missing link, in as much as (to my understanding) the jury's still out.
My question rephrased then:
Is it yet accepted that Ardi was Lucy's direct ancestor?
So the classic idea is that two different species cannot interbreed and produce fertile offspring.
We'll put aside how specific that seems to be to larger animals and how you might apply that to asexual reproduction
Let's consider Dogs - they can interbeed with Wolves notionally a seperate species and If you found a Dachund fossil and a Labrador one nobody would try and tell you they were the same species.
Then let's look at lions and tigers - Clearly seperate species?
Yet they can interbreed and the female offspring are fertile so you can have Li-tigons and ti-ligers and all sorts.
I think Waldo referenced a list of known seperate species that can interbreed (cant find it immediatly) a while back - it was reasonably long.
So this leads me to the question of what a complete fossil record would look like - what's missing? - or can you just go on forever saying "oh we're looking for the missing link between this one and the last one that was found"
We'll put aside how specific that seems to be to larger animals and how you might apply that to asexual reproduction
Let's consider Dogs - they can interbeed with Wolves notionally a seperate species and If you found a Dachund fossil and a Labrador one nobody would try and tell you they were the same species.
Then let's look at lions and tigers - Clearly seperate species?
Yet they can interbreed and the female offspring are fertile so you can have Li-tigons and ti-ligers and all sorts.
I think Waldo referenced a list of known seperate species that can interbreed (cant find it immediatly) a while back - it was reasonably long.
So this leads me to the question of what a complete fossil record would look like - what's missing? - or can you just go on forever saying "oh we're looking for the missing link between this one and the last one that was found"
I didn't suggest the fossil record was complete I merely asked what a complete fossil record would look like - what are we missing?
The point is that the very notion of species - saying this is a member of one species and that is not is at the very least questionable.
The idea of a fossil record is based on the idea of species and our ability to distinguish them.
As I pointed out with the dogs analogy this is also questionable
The point is that the very notion of species - saying this is a member of one species and that is not is at the very least questionable.
The idea of a fossil record is based on the idea of species and our ability to distinguish them.
As I pointed out with the dogs analogy this is also questionable
I punctuted my question badly, 12thPaladin. I should have asked what you mean by THE missing link. If we go back 6 million years we arrive at the common ancestor of humans and chimps. Is that the link you mean? Back another million years and we get the common ancestor of chimp, human and gorilla. Is it that one?
I cannot imagine how many common ancestors there are between homo sapiens and bacteria, let alone the original primitive life. Which is why I always ask what people (and the popular press) mean by "the missing link".
I cannot imagine how many common ancestors there are between homo sapiens and bacteria, let alone the original primitive life. Which is why I always ask what people (and the popular press) mean by "the missing link".
