I'm nearing the end of work on a review of the case for human evolution. I've uploaded some of the diagrams to my Flickr account before. Some of these were just updated and some new ones were added: see The Case for Human Evolution (Flickr set).
This is probably my favorite of the lot, showing the congruence between morphological/paleontological data (including radiometric dates) and genetic data (including molecular clocks):
(Click to see full size.)
Can you spot the single discrepancy? (No fair reading the caption on Flickr first.)
UPDATE: Revised some of the images, temporarily removed one.
What's up with Sahelanthropus? Please kick it out of our lineage!!
ReplyDeleteI would love to, however, this diagram is necessarily based on published cladistic analyses, and I could only find one that includes Sahelanthropus, and it places it as the basalmost stem-human. If you know of a published cladistic analysis that places it outside the human-chimpanzee crown group, then please let me know. (I agree that that is probably where it belongs.)
ReplyDeleteHow come no Ardipithecus kadabba or Orrorin? Have they not been included in a cladistic analysis? Those taxa line up quite nicely with the molecular estimate for the chimp/human split.
ReplyDeleteWhat taxa do you include in Australopithecus - just africanus and anamensis?
sorry - meant to say afarensis, NOT anamensis
ReplyDeleteafarensis is the type of Praeanthropus, so I couldn't very well be including that if I'm still using Praeanthropus. I'm just using it for africanus which I admit is atypical, but I generally prefer to split when possible. (Indeed, I considered including Zinjanthropus as well.)
ReplyDeleteAnd, yes, no A. kadabba or Orrorin because nobody has ever included them in a cladistic analysis. (To my knowledge, anyway--I would be ecstatic to learn otherwise.) Paleoanthropologists need to do more cladistic analyses!
And yes, they do line up very nicely with the split predicted by molecular clocks....
ReplyDeleteSorry - wasn't aware that some folks had coined a new genus name for afarensis. If you accept Praeanthropus, where do anamensis, garhi, and bahrelghazali fall in the mix?
ReplyDeleteTechnically, Praeanthropus was coined for a species called Praeanthropus africanus, which is not the same as Australopithecus africanus. The holotype specimens of Praeanthropus africanus and afarensis seem to belong to the same species, though, and the name afarensis has been conserved in spite of it being younger.
ReplyDeleteIf you like your genera monophyletic, then you don't have any good options for anamensis, which probably falls outside of Clade(afarensis + sapiens). In fact, you may have no options for afarensis, either, since it might be ancestral to any or all later genera! This is a serious problem with the idea that genera must be monophyletic.
bahrelghazali is supposed to be close to afarensis. garhi is pretty much anyone's guess. The analysis I used (Strait & Grine 2004) had tchadensis, ramidus, anamensis, afarensis, garhi, africanus as serial outgroups to the Paranthropus-Homo clade. Seeing as it's right between the types of Praeanthropus and Australopithecus I could have nudged it either way, but I elected to place it in Praeanthropus (hence that genus extending to such a late time).
And just to clarify my unusually strict usage of Australopithecus: we're in the sort of unfortunate position where there is a species (africanus Dart 1925) which seems to be close to the "nexus" of four other genera (the basal Praeanthropus and the derived Homo, Paranthropus, and Zinjanthropus), and that species is the type of a very popular generic name (Australopithecus). If you expand it, you have to make it include either 1) the type and a bunch of more basal forms (Praeanthropus), 2) the type and a bunch of more derived forms (Paranthropus and possibly Zinjanthropus), or 3) all post-ramidus, non-Homo stem-humans. Options #1 and #2 form a kind of arbitrary toss-up. Option 3 obscures some marked cladogenesis going on with Paranthropus (?=Zinjanthropus). Thus, I am regrettably left with option 4: a very strict usage of Australopithecus.
ReplyDeleteHave I mentioned how much I hate binomial nomenclature?
Given that everyone working on palaeoanthropology seems to love naming new species and genera anyway, we should just make all genera (in this part of the ToL) monotypic. The number of extra generic names that'd need to be coined would not be large.
ReplyDeleteIncidentally, I totally forgot about Paraustralopithecus (typified by aethiopicus).
ReplyDeleteWell, not counting the species in Homo (of which I think only two are types of genera: erectus and sapiens), you'd need new names for kadabba, anamensis, bahrelghazali, and garhi.
Another solution is to just drop the damn generic praenomina as long as you're working in a context where the epithets are distinctive. (Happily, Praeanthropus africanus has been obliterated in favor of Australopithecus africanus.) I think you're safe until you get out to a clade including Proconsul africanus (a stem-hominoid, IIRC).
I should also mention that habilis and rudolfensis have both been placed outside of Homo by some authors (Australopithecus habilis and Kenyanthropus rudolfensis, IIRC). Others consider them the same thing. Gah!
ReplyDeleteI agree that H. habilis is the same as H. rudolfensis because all features separating them are also found in sexually dimorphic catarrhines. In addition, some features widely used to separate the two do, in fact, not exist. \
ReplyDeleteBut to make every genus monotypic might be a bit of a stretch. I admit that parts of the tree might be oversplit, but at the same time, some might be undersplit. It is a mess at the moment that is predominantly created by the inability for many specialists to cooperate with authors due to very different, and most importantly, strong opinions.
Interesting, so which is the male and which is the female?
ReplyDeletePaleoanthropology is rife with emotional/personal arguments compared to other fields in paleontology. (Although those same fields were pretty rife with them a generation or two ago as well.) Hopefully paleoanthropology catches up in the next generation.
H. habilis is female and H. rudolfensis is male. However, this is not a hard-and-fast rule, because some smaller crania are referred to H. habilis , but are actually small (immature) males (e.g. OH 16).
ReplyDeleteRight, sorry, I just meant the holotypes.
ReplyDeleteHere is a cladistic analysis that includes Orrorin and Ardipithecus... But they have some "odd" results :P...
ReplyDeletedoi: 10.1111/j.1365-2699.2009.02141.x
By the way, how the "ancestal maps" were calculated?
Ah, yes, Schwartz ... thanks, but, um, no thanks. :)
ReplyDeleteThe maps were not done rigorously, just by eyeballing average loci and then establishing an arbitrary perimeter. I may readdress this.
I'll definitely be readdressing the portion of the above chart outside the African ape crown clade.
Wait, or are you referring to the haplogroup maps? Those were done with GraphViz -- each haplotype is invisibly linked to its (invisible) region(s).
ReplyDelete