5 ms·

My impression is that we just don't have enough data to draw an accurate timeline, much less a tree, and are an order of magnitude away from being able to study

My impression is that we just don't have enough data to draw an accurate timeline, much less a tree, and are an order of magnitude away from being able to study second-order phenomenon like introgression. I think fewer than 10,000 early hominid individuals have been found, most with very partial skeletons. And they aren't distributed uniformly across time and space; you might find a dozen in one cave, then nothing for thousands of years, or nothing on an entire continent. "You could fit it all into the back of a pickup truck if you didn't mind how much you jumbled everything up." - Ian Tattersall https://www.goodreads.com/quotes/6578939-since-the-dawn-of-time-several-billion-human-or-humanlike https://www.goodreads.com/quotes/6578939-since-the-dawn-of-t... It also seems like every time they find a new fossil, they change their mind about how everything fits together. I am not an expert in this field, but if I had a small dataset and I fit a very complex model to it with literally hundreds of free parameters and I found that the model completely changed every time I added a few new data points and re-fit, then I would conclude I was dealing with a high-variance model that was overfitting the data and either use a simpler model or wait until I had collected much more data before trying to fit such a complex model.

not_a_cop75 7y ago
Is it wrong to believe at this point that instead of macro evolution, we could be looking at several differing extinction points?
- BurningFrog 7y ago
  I think the point is that we know so little that we might look at a huge number of wildly different scenarios. So... keep digging!
  - subsaharancoder 7y ago
    Or..that we need more faith to believe in evolution than to believe in creation
    - bigbluedots 7y ago
      Maybe, but creation has zero evidence in its favor
- deleted 7y ago
  [deleted]
- dwaltrip 7y ago
  I believe "macro evolution" is a bit of a controversial term, as it that term and the corresponding "micro evolution" have been co-opted by creationists, who obtusely claim that there is no evidence for macro evolution, but that they accept micro evolution. I'm reading "The Greatest Show on Earth" (which is a fantastic book for a broad overview of the evidence for evolution. The evidence is truly astounding and awesome). Dawkins spends a bit of time arguing that the distinction between micro and macro isn't that meaningful. However, I just skimmed the Wikipedia pages and it seems the terms may have some legitimate usage? Perhaps his unfortunate dealings with creationists have simply spoiled the terms for him.
dalbasal 7y ago
Definitely not enough to draw an accurate timeline, but enough for educated guesses. As you say, guestimates shift with major discoveries, but not quite as much as pop-science press would have you think. This species is now the oldest known australopithecine, by a hair. It is a contemporary and possible ancestor of afarensis. It's true that we don't know (and probably won't because it's too old for DNA) if these fossils just represent diversity in a species, subspecies or several species. We do know that they're similar to each other. We also know that they existed 4mya. Divergence from chimps is thought to have happened around 6-7mya (also controversial, and subject to change). So... all the australopithecines at that time were probably genetically compatible, considering apes slow breeding and how long it takes most large mammals to completely speciate. Considering how different they are from chimps and similar they are to each other, it's a decent guess that they are closely related. We know that the genus had at least 5 types/subspecies/species, 6 if we include habilis. Baboons occupy a similar niche to australopithecines. There are 5 closely related species. They hybridize often, but still maintain these separate species/types, probably because it's adaptive in their respective ecosystems. It's meaningful that australopithecines had a similar pattern. An interesting side point is that there's some speculation that baboons emerged once australopithecines (inc habilis) declined, homo (erectus) emerged and the ecological niche became free. So yes, we can't tell exactly which of these extremely closely related types represent distinct "species" and which of these is our immediate ancestor. But, that's more semantics than substance. We have pretty strong evidence that early homo was an australopithecine type, within a closely related (recently emerged) genus.. and that there was probably a lot of hybridization within the genus. There's a lot to the difference between definitive knowledge and no knowledge.

not_a_cop75 7y ago

Is it wrong to believe at this point that instead of macro evolution, we could be looking at several differing extinction points?

BurningFrog 7y ago
I think the point is that we know so little that we might look at a huge number of wildly different scenarios. So... keep digging!
- subsaharancoder 7y ago
  Or..that we need more faith to believe in evolution than to believe in creation
  - bigbluedots 7y ago
    Maybe, but creation has zero evidence in its favor
deleted 7y ago
[deleted]
dwaltrip 7y ago
I believe "macro evolution" is a bit of a controversial term, as it that term and the corresponding "micro evolution" have been co-opted by creationists, who obtusely claim that there is no evidence for macro evolution, but that they accept micro evolution. I'm reading "The Greatest Show on Earth" (which is a fantastic book for a broad overview of the evidence for evolution. The evidence is truly astounding and awesome). Dawkins spends a bit of time arguing that the distinction between micro and macro isn't that meaningful. However, I just skimmed the Wikipedia pages and it seems the terms may have some legitimate usage? Perhaps his unfortunate dealings with creationists have simply spoiled the terms for him.

dalbasal 7y ago

Definitely not enough to draw an accurate timeline, but enough for educated guesses. As you say, guestimates shift with major discoveries, but not quite as much as pop-science press would have you think. This species is now the oldest known australopithecine, by a hair. It is a contemporary and possible ancestor of afarensis. It's true that we don't know (and probably won't because it's too old for DNA) if these fossils just represent diversity in a species, subspecies or several species. We do know that they're similar to each other. We also know that they existed 4mya. Divergence from chimps is thought to have happened around 6-7mya (also controversial, and subject to change). So... all the australopithecines at that time were probably genetically compatible, considering apes slow breeding and how long it takes most large mammals to completely speciate. Considering how different they are from chimps and similar they are to each other, it's a decent guess that they are closely related. We know that the genus had at least 5 types/subspecies/species, 6 if we include habilis. Baboons occupy a similar niche to australopithecines. There are 5 closely related species. They hybridize often, but still maintain these separate species/types, probably because it's adaptive in their respective ecosystems. It's meaningful that australopithecines had a similar pattern. An interesting side point is that there's some speculation that baboons emerged once australopithecines (inc habilis) declined, homo (erectus) emerged and the ecological niche became free. So yes, we can't tell exactly which of these extremely closely related types represent distinct "species" and which of these is our immediate ancestor. But, that's more semantics than substance. We have pretty strong evidence that early homo was an australopithecine type, within a closely related (recently emerged) genus.. and that there was probably a lot of hybridization within the genus. There's a lot to the difference between definitive knowledge and no knowledge.