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Author Topic:   New Human Fossils found
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(2)
Message 6 of 31 (670252)
08-10-2012 11:48 PM
Reply to: Message 5 by Artemis Entreri
08-10-2012 6:18 PM


Re: right on
Hi, Chaoticskunk.
chaoticskunk writes:
the only comment I have is: they specifically mention a time when there were e species of Homo alive, yet when you look at the graph it clearly shows a time period when there were FOUR (erectus, ergaster, habilis, and rudolfensis). Strikes me as weird to mention 3 as news especially when we think the youngest 3 (sapiens, neanderthalensis, and erectus) lived at the same time.
As far as I'm aware, Homo erectus and H. ergaster are not generally considered to be all that distinct from one another (erectus are basically just ergaster that lived outside of Africa). And, given current evidence, Neanderthal is probably more appropriately regarded as a subspecies of H. sapiens.
But, the difference here is that ergaster, rudolfensis and habilis were living at the same time and in the same region (southern/eastern Africa), whereas Neanderthal, sapiens and erectus were separated geographically.
Edited by Blue Jay, : underline code

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 5 by Artemis Entreri, posted 08-10-2012 6:18 PM Artemis Entreri has replied

Replies to this message:
 Message 8 by Artemis Entreri, posted 08-12-2012 12:40 PM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 10 of 31 (670324)
08-12-2012 6:37 PM
Reply to: Message 8 by Artemis Entreri
08-12-2012 12:40 PM


Re: right on
Hi, Chaoticskunk.
chaoticskunk writes:
I am not a geneticist but I am not sure about that. I think Sapiens and Neaderthalensis are decendants of Heidelbergensis, making them more on the same level rather than one being a sub species of another.
Homo heidelbergensis was likely also the same species. Neanderthal genes have been found in most modern humans, indicating that some level of interbreeding occurred: this suggests that Neanderthal and sapiens are closely-related enough to be considered the same species.
It all depends on where you want to draw your arbitrary lines.
chaoticskunk writes:
I see not geographical difference. I think sapiens encountered both, and I know Erectus were in Europe, but did the other two exist when they were is more the real question.
I think the only "European" Homo erectus known is from the Caucasus, and it was from well before the first Neanderthals or heidelbergines began to appear there.
And, it isn't about whether the three species ever encountered each other. Homo erectus evolved in Africa and expanded into Asia. Meanwhile, heidelbergensis evolved in Africa, then expanded into Europe, and gradually diverged into a European form (neanderthalensis) and an African form (sapiens). At some later point in time, sapiens expanded and came into contact with the other species, but only after they had been partially isolated for some time, and had already evolved into distinct "species" during their isolation.
By comparison, habilis, rudolfensis and ergaster not only lived in the same location at the same time, but also apparently evolved into distinct "species" in the same location and at around the same time. This is called "sympatric speciation": something other than geography was a barrier to interbreeding between these "species."

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 8 by Artemis Entreri, posted 08-12-2012 12:40 PM Artemis Entreri has replied

Replies to this message:
 Message 11 by Dr Adequate, posted 08-12-2012 7:01 PM Blue Jay has replied
 Message 13 by caffeine, posted 08-13-2012 3:23 AM Blue Jay has replied
 Message 16 by Artemis Entreri, posted 08-13-2012 12:10 PM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 12 of 31 (670333)
08-12-2012 9:30 PM
Reply to: Message 11 by Dr Adequate
08-12-2012 7:01 PM


Re: right on
Hi, Dr A.
Dr Adequate writes:
Blue Jay writes:
Meanwhile, heidelbergensis evolved in Africa, then expanded into Europe, and gradually diverged into a European form (neanderthalensis) and an African form (sapiens).
If this is actually known by anyone, I should like to see the evidence.
Well, I suppose I should be more careful.
There's an African form (sapiens) and a European form (neanderthalensis), and heidelbergensis (also European) seems intermediary between the two and also shares particular affinities with other African forms (ergaster and rhodesiensis).
Technically, it's possible that heidelbergensis evolved in Europe (presumably an offshoot of Asian erectus) where it eventually evolved into neanderthalensis; while an offshoot of heidelbergensis expanded back to Africa, whereupon it evolved into rhodesiensis and sapiens, the latter of which migrated back to Europe.
It's also possible that heidelbergensis is the ancestor of neanderthalensis, but not of sapiens, in which case sapiens evolved from ergaster or rhodesiensis (or both).
But, none of this is particularly relevant to my overall point, so I just went with the model that was easiest to explain in a single sentence, so I could get on with it.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 11 by Dr Adequate, posted 08-12-2012 7:01 PM Dr Adequate has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 19 of 31 (670418)
08-14-2012 11:32 AM
Reply to: Message 16 by Artemis Entreri
08-13-2012 12:10 PM


Re: right on
Hi, Chaoticskunk.
Chaotincskunk writes:
I am not saying you are wrong, but I think erectus came to europe and then evolved into heidelbergensis. More due to the pakefield dates and the consensus on the earliest heidelbergensis dates. I agree its arbitrary and spitting hairs, but then why else are we here talking about this stuff?
And you could very well be right: I'll freely admit that I don't know.
But, the main thread of discussion was the coexistence of multiple hominin species. Homo erectus and H. ergaster existed across a large swathe of the Old World, and populations in different regions diverged into distinct lineages. Ultimately, these lineages encountered one another when one of them (H. sapiens) expanded out of its ancestral range.
The three "species" found in Kenya around 1.7 Mya showed a similar pattern of coexistence, but on a much smaller geographical scale. This implies that there must have been a different type of mechanism isolating these "species" from each other. For example, they may have preferred different habitats, or they may have evolved in different sub-regions within the same region.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 16 by Artemis Entreri, posted 08-13-2012 12:10 PM Artemis Entreri has replied

Replies to this message:
 Message 21 by Artemis Entreri, posted 08-14-2012 12:17 PM Blue Jay has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 20 of 31 (670419)
08-14-2012 11:40 AM
Reply to: Message 13 by caffeine
08-13-2012 3:23 AM


Re: right on
caffeine writes:
Or, rudolfensis and ergaster could both have evolved in small, geographically isolated regions outside the notice of palaentology, at least up till now, before expanding back into the rest of Africa. Is there anything I've missed that argues against this alternative?
I'm not sure. Just in terms of pure rationalism here, evolution into distinct lineages on a small geographic scale would suggest some measure of sedentarism. But, both habilis and erectus/ergaster had rather wide geographical distributions, which, to me, works against the notion of geographic isolation on a small scale.
However, since rudolfensis is only known from Kenya, small-scale geographic isolation is a very good hypothesis for their evolution.
Edited by Blue Jay, : quote tags

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 13 by caffeine, posted 08-13-2012 3:23 AM caffeine has not replied

  
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