Summary of hominin evolution

[Anonymous]

Roger, feel free to post this on the Wiki. It is a summary of hominin evolution which I have posted at http://www.antiquityofman.com/hominin_e ... mmary.html . These are various page links within the summary (see the original)


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Summary of hominin evolution
by Mikey Brass

Despite the abundance of quality "coffee-table" archaeological books on the market, the public in general display a remarkable ignorance (intentional and unintentional) of the basic fundamentals of the history of our own lineage, let alone the intricacies of past and current theories, paradigms and debates.

This is true in my birthland of South Africa: only really since 1997 have bookshops been stocking archaeological books of good quantity and, equally importantly, good quality. Sadly I have found, through bitter experience, this occurrence to be equally common in many towns, cities and countries across the globe; the worst case is, ironically, America with its appalling scientific education system and the powerful, idiotic, fundamentalist, religious right. Regrettably, universities are not much better at providing information on their websites, although the time passed since this website was launched has seen a vast improvement. Although there are Internet courses offered by some universities in archaeology, many people either cannot afford them or do not have the time to study, or in other cases both.

To this end a site like Talk Origins fills the blank on the Internet informatively, with its particular emphasis on debunking the pseudoscientific myths of creationism. It is weaker in outlining some of the debates presently argued in academic circles and in scholarly journals, as well as summarising a determined selection of current research paradigms and the results generated from the earliest hominins right down to the present.

A combination of the genetic and fossil evidence point to the last common ancestor of humans and chimpanzees living in East Africa between 8 - 6 million years ago (mya). The currently oldest classified hominin fossil in the published literature is that of Sahelanthropus tchadensis at 7.4 - 6.4 mya (millions of years ago). The two next oldest hominins are Ardipithecus ramidus kadabba, dated at 5.6 mya, Ardipithecus ramidus at 4.4 mya and Orrorin tugenensis at 5.7 - 6 mya. For the next three million years australopiths occupied various ecological niches in East, Central and Southern Africa. At roughly 2.5 million years ago the first stone tools (termed the "Oldowan Industry") are evident in the archaeological record. This coincides with the appearance of the disputed Homo habilis. The new skill was copied by their australopith contemporaries. Homo erectus is descended from Homo habilis and, around 1.8 mya, migrated first into the Near East, then into Asia and finally later from the Near East up into Europe.

The modern debate surrounding the origins of anatomically modern humans has traditionally been associated, in the public's eyes, with two models: the Multiregional and the strict Out-of-Africa. Less commonly known are the Assimilation (Fred Smith) and mild Out-of-Africa (Brauer) models. The strict Out-of-Africa model is contradicted by anatomical and genetic data; although still espoused by some scholars (for example, Paul Mellars), it is generally regarded as flawed. There are also questions marks over the validity of the form of Multiregionalism as espoused by Wolpoff, Hawkes and others. The main difference between Brauer and Smith's models is the degree of postulated interbreeding. To me it is clear from the available evidence that late archaic hominins interbred. Eric Trinkaus concluded his recent survey of the genetic and anatomical data in the 2005 issue of the Annual Review of Anthropology by stating that "the issue has increasingly become whether one can perceive the ancestry of non-African late arcahic humans (especially of the Neandertals) in the biology of living humanity. This is not a question addressing the evolutionary processes involved in the emergence of modern human biology. This is a question regarding the evolutionary purity of living humanity. This...confuses the human population dynamics of 30-100 millennia ago with the complex human population history of the past 30 millennia. Given the human demographic dynamics associated, minimally, with the climatic and ecozonal changes of the last glacial maximum (OIS 2), the development of food-producing societies, the rise and interaction of complex societies, and the globalization of the human population during the past two millennia, it remains curious how one can even pose the...question. The only justification would be a macroevolutionary approach in which all past and present "modern" humans are perceived as the same; such a perspective is typological and irrelevant to the populational processes involved in the establishment of modern humanity... Two dozen years ago, human paleontologists suggested that modern humans originated in equatorial Africa and subsequently expanded into at least western Eurasia, variably absorbing regional late archaic human populations in the process. After two decades of debate, the field has come to the concensus that modern humans originated in equatorial Africa and subsequently expanded into Eurasia and the remainder of Africa, variably absorbing regional late archaic human populations in the process. This is known as the assimilation model. Versions of the assimilation model have remained contenders for the interpretation of modern human phylogenetic emergence, if frequently overshadowed by the more polarized regional contintuity (with gene flow) and (out of Africa with) replacement scenarios. The last two interpretations are finally intellectually dead. Both are contradicted by available evidence, and it is time for the discussion to move on... The question can therefore be rephrased to ask, to what extent can the early modern human paleontological record and other data help refine the regional biological, behavioral, and chronological details of the assimilation model?"

It is, literally, the exploration of a lifetime.

[Timothy Chase]

I must confess that human evolution is one of my real weaknesses. I am much more at home in articles on nucleic acids, the evolution of phages or evolutionary developmental biology, and even there I regard myself as a rank amateur. However, with very little work (perhaps just a fleshing out where there are currently ellipses), I believe this could be made the first paper in a section on human evolution.

Then there are numerous websites that we could reference where the bush of human evolution is presented, the various species leading up to modern man. Likewise, we could start indexing science news stories and technical papers relating to the discoveries regarding human evolution - as part of the same section of the Wiki, distinct from the main links pages. Plenty of this sort of material is on the net and accessible as well if people know where to find it.

In essence, I believe that the website needs plenty of its own material, and Roger has done a real bangup job where it is most critical - namely, in tracking down, documenting the main players and organisations and identifying the connections between them which together have created creationist assault upon UK education. However, we need to leverage what has already been done elsewhere, and this means that at the bottom of the main sections, we should have links to articles within our own Wiki followed by links to other related material on the web. In this way, we can turn the BCSE into a hub for the kind of information that people will find especially useful in opposing the creationists.

Moreover, I realise that we are somewhat limited in the pictures that we are able to present at the website itself. This is partly for lack of the capacity, and partly for the lack of the photos themselves - at least photos that we have the legal rights to use. Linking to websites which do have such photos will be particularly helpful until we are able to remedy this.

After a while, particularly with the short attention span of internet readers, words become just words, their eyes begin to glase over, and one argument seems no better than another - but pictures bring them back to the point that we are talking about a real world where things are what they are indepedently of how many or how vociferously creationists might deny it and what took place in the past has left evidence which is still visible today. Pictures help stress this, emphasising that what is real is real, giving them a break from the text, then letting them return to it with renewed interest and attention.

[Anonymous]

Timothy Chase wrote:

However, with very little work (perhaps just a fleshing out where there are currently ellipses), I believe this could be made the first paper in a section on human evolution.

I should mention a few things. The first is that I read widely in the
discipline as indeed my interests range from early hominin evolution
right down to recent rock art, genetic studies and ethnography. This has
the disadvantage of limiting my already limited time even further,
particularly as my main research focus is the archaeology of North
Africa (I have a paper being published next year). However, I am finally
able to get around to reading the papers on the Dikika child and plan,
over the weeks, to write up a summary for my website
(http://www.antiquityofman.com) which I will post on the BCSE wiki as well.

To get back to your point about developing an full hominin evolution
section on the wiki. I don't believe that is necessary. There will be
summary pieces posted over time but Talkorigins does such a brilliant
job of refuting the creationist rubbish on this topic that I have no
desire to duplicate the effort. Instead, I would prefer to link this
section of the wiki with talkorigins' pages
(http://www.talkorigins.org/faqs/homs/), with the addition of selected
pieces when I find the time.

[Timothy Chase]

..., to write up a summary for my website
(http://www.antiquityofman.com) which I will post on the BCSE wiki as well.

This sounds good - and of course the essay which you have already written will I am sure be a welcome addition to the Wiki.

To get back to your point about developing an full hominin evolution section on the wiki. I don't believe that is necessary. There will be summary pieces posted over time but Talkorigins does such a brilliant job of refuting the creationist rubbish on this topic that I have no
desire to duplicate the effort. Instead, I would prefer to link this section of the wiki with talkorigins' pages (http://www.talkorigins.org/faqs/homs/), with the addition of selected pieces when I find the time.

I like that idea a great deal as well.

In fact, whether the section on human evolution is a single page or several pages, ideally it should have links to additional resources - since a great deal of the value in any good website lies in the connections it makes to other resources. We should definitely include links to the most relevant parts of the TalkOrigins website - and a link to your own website - as part of a "To Learn More/External Links" section near the bottom of the webpage on human evolution. I might also like to see a webpage on recent discoveries with links to relevant news items and papers, but that is something we might consider at a later time.

[Anonymous]

and of course the essay which you have already written will I am sure be a welcome addition to the Wiki.

If you are referring to my forthcoming journal article, the only content which will appear online (for the next couple of years) on my site is the abstract. Also, its topic is not of direct relevance to the Wiki.

In fact, whether the section on human evolution is a single page or several pages, ideally it should have links to additional resources - since a great deal of the value in any good website lies in the connections it makes to other resources. We should definitely include links to the most relevant parts of the TalkOrigins website - and a link to your own website - as part of a "To Learn More/External Links" section near the bottom of the webpage on human evolution. I might also like to see a webpage on recent discoveries with links to relevant news items and papers, but that is something we might consider at a later time.

Agreed on the former, hesistant on the latter. Jim Foley (talkorigins) attempted to do exactly that for a number of years and it ends up being unworkable. Instead, a link to http://www.antiquityofman.com/journal_summaries.html would work just as well.

[Scott]

Hi All,

Here's a tidbit some of you might find of interest.

Oldest Complex Organic Molecules Found In Ancient Fossils

http://researchnews.osu.edu/archive/foscolor.htm

Ohio State University geologists have isolated complex organic molecules
from 350-million-year-old fossil sea creatures -- the oldest such
molecules
yet found. The molecules may have functioned as pigments, but the study
offers a much bigger finding: an entirely new way to track how species
evolved. Christina O'Malley, a doctoral student in earth sciences at
Ohio
State, found orange and yellow organic molecules inside the fossilized
remains of several species of sea creatures known as crinoids. The
oldest
fossils in the study date back to the Mississippian period.

Cheers,
Scott

[Timothy Chase]

We have also found embryos from 560 million years ago - with fossilised cells and organelles which can be examined using electron microscopes. The embryos are evidentally from before the vertebrate/invertebrate split, and as such would be representative of the common ancestor of - for example - ants and ardvarks.

See:

PZ Meyers on the Dawn of Metazoans
http://bcseweb.org.uk/forum/viewtopic.php?t=186