john hawks weblog

paleoanthropology, genetics and evolution

Homo erectus

  • Palming Homo erectus

    Sun, 2013-04-14 17:22 -- John Hawks

    New Scientist reports on Carol Ward's presentation at the AAPA meetings, describing a new metacarpal of Homo erectus from West Turkana: "Stone tools helped shape human hands". It is a third metacarpal, a bone that happens to be pretty different between known australopithecines and recent Homo. But strikingly none have yet been described for Homo before the Neandertals.

    Because the fossil is younger than the first tools, Ward's team believe it is the first evidence of anatomy evolving to suit a new technology. As stone tools became more widespread, those who had the wrist structure to use them would have had an evolutionary advantage over their weaker-wristed kin. "The way we look today has been shaped by our behaviour over millions of years," says Ward.

    The developmental change represented by this anatomy is a separate center of ossification at the base of the metacarpal leading to a pointy projection called the styloid process. That's a pretty interesting shift in development, and so I'm intrigued that it came closely after the appearance of Homo erectus. Ward also reported that the bone is very long, at the top end of the variation in living people and longer than any Neandertals. Another hint of big people in the Early Pleistocene of East Africa.

    Tags: 
    Homo erectus
    fossils
    morphology
    stone tools
    Kenya
    West Turkana

  • Mandibles of early Homo and robust australopithecines

    Mon, 2012-11-12 22:36 -- John Hawks
    Synopsis: 
    A lab showing the variation of mandibles in early members of our genus.

    For anthropologists, Africa was a point of exceptional diversity between 2 million and 1.5 million years ago. In both East and South Africa, the fossil record presents evidence of several different hominin species. Some fossils belong to our own genus, Homo, and others belong to robust australopithecines.

    These two forms seem like they should be easy to tell apart. Robust australopithecines had extraordinarily large mandibles compared to living humans. Consider:

    • The main part of the mandible, which holds the teeth, is called the mandibular corpus. In robust australopithecines, this is often extremely thick and tall, with a large distance from the inferior border of the mandible to the teeth.
    • The portion of the mandible that extends upward to articulate with the temporal bone is called the mandibular ramus -- with one on both left and right sides. The mandibular ramus of many robust australopithecines is exceedingly tall, reflecting the very vertically tall faces of these hominins.
    • Robust australopithecines have hugely expanded premolars and molars, and greatly reduced incisors and canines. Early Homo has overall larger teeth than in living humans, but the proportions between the molars, premolars, incisors and canines is very much like people today.

    However, despite these obvious differences, the mandibles of early Homo and robust australopithecines are not always so easy to tell apart. This station has several mandibles from robust australopithecines, mainly from Australopithecus robustus from Swartkrans and Kromdraai, South Africa. There are also several mandibles of Homo erectus here, and a handful of mandibles that are likely early Homo but not definitely H. erectus.

    Can you tell them apart? Try seriating these from most humanlike to most robust australpithecine-like. Is there a clear dividing line between the two, or are there questionable specimens?

    Study terms: 
    ramus
    corpus
    Australopithecus robustus
    Homo erectus
    Swartkrans
    Kromdraai
    Sangiran
    Tags: 
    mandible
    Anthropology 105
    laboratory
    anatomy
    Homo
    Homo erectus
    Australopithecus robustus
    Kromdraai
    Swartkrans
    Sangiran

  • Panda gestion

    Sun, 2012-10-14 20:25 -- John Hawks

    Here's a story that showed up in my feed this morning: "Prehistoric man ate panda, claims scientist".

    Wei Guangbiao said prehistoric man ate the bears in what is now part of the city of Chongqing in south-west China.

    Wei, head of the Institute of Three Gorges Paleoanthropology at a Chongqing museum, said excavated panda fossils "showed that pandas were once slashed to death by man".

    This really wouldn't be very surprising, as occasional evidence of human predation or consumption of other carnivores, including bears in Europe, goes way back.

    Tags: 
    pandas
    China
    Homo erectus
    meat
    diet

  • Koobi Fora perspectives

    Fri, 2012-08-10 17:28 -- John Hawks

    I'm in Kansas and my internet is spottier here than it was in Africa. So I have a bunch of thoughts about the new Koobi Fora fossils published by Maeve Leakey and coworkers this week [1], and I have to wait to document them all. It just so happens that I was looking closely at a cast of the KNM-ER 1802 mandible with Lee Berger last week, comparing it to some of the Sterkfontein mandibles. There's a very interesting story there about variation in fossil samples of Australopithecus and (supposedly) early Homo.

    I can't tell it yet properly. So in the meantime, I highly recommend two takes on the new fossils from two experts. Zach Cofran, who has just finished his Ph.D. and set off for a new faculty position in Kazakhstan, asks a question the Nature paper didn't: How does the new KNM-ER 62000 face compare to the otherwise very Homo-like A. sediba? ("These new fossils are as intriguing as hell") Amazing what a simple photo montage can tell you...

    Adam Van Arsdale has his own substantial base of expertise coming from the Dmanisi sample of early Homo erectus, where the mandibles encompass an incredible range of morphological variation, especially with respect to mandibular size and robusticity: "The new Koobi Fora early Homo fossils".

    Prior to the publication of KNM ER-60000, the Dmanisi 2600 mandible was truly exceptional in many respects relative to other mandibles assigned to early Homo. In particular, the size of its corpus and height of its ramus stood out. This new specimen from Kenya, dating from a similar time, is the best match we have yet for its features. And yet it is being linked to a fossil, KNM ER-62000, that has notable affinities (despite a significant difference in size) with KNM ER-1470, a fossil that prior to this publication also appeared somewhat morphologically exceptional relative to its peers. The authors also note similarities bewteen the new lower face (KNM ER-62000) and the Dmanisi 2700 individual. So in some ways, these fossils seem to be filling in a gap between earlier African material associated with habilis/rudolfensis and Dmanisi. And yet Dmanisi has already been widely associated with later African and Asian material assigned to Homo erectus, hence the description of it in various publications as basal Homo erectus.

    My only exception to Adam's perspective is that the Koobi Fora sample itself already contains a lot of mandibular diversity. In Georgia, we have the luxury of knowing that none of the mandibles represent Australopithecus boisei, meaning that we recognize a robusticity in early Homo that may have been sifted out of descriptions of the East African sample. The earlier South African sample also has huge mandibular diversity. I think it is premature to sort these East African fossils into four or more species on the basis of one or two new specimens.

    But more later.

    References

    1. Leakey MG, Spoor F, Dean CM, Feibel CS, Antón SC, Kiarie C, Leakey LN. New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo. Nature. 2012;488(7410):201-4.
    Tags: 
    Homo erectus
    Homo habilis
    Homo rudolfensis
    Koobi Fora
    East Africa
    Early Pleistocene

  • African Homo erectus

    Tue, 2011-11-08 00:14 -- John Hawks
    Synopsis: 
    African specimens from the Early Pleistocene are compared

    This station includes several casts of early fossil Homo erectus, from the Early Pleistocene of Africa. These include:

    • OH 9, from Olduvai Gorge, Tanzania, around 1.2 million years old.
    • KNM-ER 3733, from Ileret, Kenya, 1.65 million years old.
    • KNM-ER 3833, from Koobi Fora, Kenya, 1.6 million years old.
    • KNM-WT 15000, from Nariokotome, Kenya, 1.5 million years old.

    In addition to these specimens, the station has a few comparative casts from earlier hominid species and from other parts of the world.

    What to do: First, consider the issue of sexual dimorphism in these specimens. Which are male and which are female? What features lead you to that conclusion?

    Second, why are the differences between these specimens and Homo habilis, for example, KNM-ER 1813, reflective of a species distinction, instead of sex?

    Study terms: 
    Nariokotome
    Koobi Fora
    Ileret
    Lake Turkana
    Olduvai Gorge
    Tags: 
    Anthropology 105
    laboratory
    explainer
    Homo erectus
    Africa
    Kenya
    Tanzania

  • Asian Homo erectus

    Mon, 2011-11-07 23:59 -- John Hawks
    Synopsis: 
    Examining a sample of crania from the Early and Middle Pleistocene of Asia and Indonesia

    Homo erectus entered Asia as early as 1.8 million years ago. One of the earliest specimens of the species is the Modjokerto skull, from Java. The spread of this species across the tropical Old World was a major event in our evolution. After Homo erectus reached East and Southeast Asia, it had a long history — up to 200,000 years ago or even more recently.

    This station has several representatives of this Asian dispersal of early humans.

    • Trinil 2, Java, 1.2 million years old.
    • Sangiran 2, Java, 1.0 million years old.
    • Zhoukoudian L2, China, 700,000 years old.
    • Zhoukoudian L1, China, 700,000 years old.
    • Ngandong 10, Java, 200,000 years old.
    • Ngandong 8, Java, 200,000 years old.
    • Nganding 4, Java, 200,000 years old.

    What to do: Overall, these fossils are very similar. However, they come from a wide range of times. Make an attempt to seriate the fossils by cranial size. List the results of your seriation. Does it correlate with time?

    Try seriating the skulls according to the form of their frontal bone or supraorbital torus. This feature differs between fossil specimens from Java and China. Does your seriation indicate this difference in geography?

    Study terms: 
    Zhoukoudian
    Sangiran
    Ngandong
    Trinil
    seriation
    Tags: 
    Anthropology 105
    laboratory
    Homo erectus
    Asia
    China
    Indonesia
    Sangiran
    Zhoukoudian

  • Through the early Homo archives

    Mon, 2011-08-29 22:32 -- John Hawks

    I've enabled the search function for the site, which you'll find at top right on each page of the site. The search index is still rebuilding, and as I write this has only indexed 4% of the site. That brings it up to late 2007, and it's interesting to go back through the history of paleoanthropology that way.

    For example, I ran across my comments ("Is a lack of fossils the problem with early Homo?") on a John Noble Wilford piece from four years ago. Seems very timely in many ways. For example, the paucity of the fossil record of Homo before 1.6 million years ago was a major feature of the article. I directed my attention to the supposed "gap" between 3 and 2 million years ago:

    [W]e actually have quite a lot of fossils from this time period. The entire South African A. africanus fossil record, with the exception of a few early specimens like STW 573, come from this "gap." A fairly extensive record of the appearance and evolution of early robust australopithecines comes from this time period in East Africa.

    And, here and there, a few specimens look Homo-like. Wilford's article discusses AL 666-1. To this we can add the Uraha mandible, Omo 75-14, an additional series of teeth from Omo, and possibly the Bouri BOU-VP 35/1 skeleton.

    Properly considered, the rarity of early Homo in these contexts is not a problem; it is information.

    Of course, dates have changed. We now have good dates for Dmanisi, which make those fossils the earliest well-attested Homo erectus sample at 1.8 million years. STW 573 now looks late, not early. But the fact remains that people were looking for pure representatives of Homo in the fragments instead of exploring morphological diversity within the large and fairly complete samples at hand.

    Tags: 
    Homo
    Homo erectus
    Sterkfontein
    A. africanus
    Hadar

  • Mailbag: Thick skulls and diet

    Tue, 2011-04-12 23:15 -- John Hawks

    Re: "Hard headed science":

    Although genetics undoubtedly play a part in the thickness of the skull bone, there is another parameter that more often than not is overlooked by anthropologists. That parameter is nutrition. Modern man is overfed on calories but malnourished on micronutrients. Soft tissues always evolve to their fullest, but the hard tissues, i.e. bone, are much more dependent on nutrition and physical work-load. Compared to the skulls of its ancestors, the skull of modern man is thinner, smaller, narrower, the eye sockets tend to be rounder and there tends to be insufficient space for the teeth in the mouth. It seems reasonable to me that in so far as the shape of the skull, it is the phenotype that’s changed, not the genotype.

    Nutrition can make a difference, but the variation in skull thickness during the last 2 centuries is very minor compared to the amount of difference between Homo erectus, Neandertals and us. The thinning also preceded any significant shift from hunting and gathering to agriculture. There has been further thinning after agriculture, so that we can't attribute the shift to a straightforward diet change.

    Tags: 
    Homo erectus
    paleopathology
    nutrition
    diet

  • Hard-headed science

    Tue, 2011-04-12 08:11 -- John Hawks

    Scicurious has been blogging from the Experimental Biology 2011 meeting. This morning she writes about some of Lynn Copes' work: "Experimental Biology Blogging: On Thick Skulls and...Chewing." Copes has kept a crew of mice on hard foods in a cold room, to get them to chew more. Would it give them thicker skulls?

    Copes found that the mice who had the soft diet had weaker jaw muscles (masseters) than those eating normal chow or chewing more in the cold, but it wasn't by much, and the skull (cranial vault) thickness did not significantly vary in any of the conditions. While this may seem like negative data, this actually suggests that, rather than the activity varying skull thickness, the thickness of our skulls may be genetically determined. Copes hopes to eventually address this question by looking at the skulls of various modern and ancient human groups. By looking at the thickness of adult skulls compared to those of children, she hopes to determine whether skull thickness is genetically determined, and if so, when, and why, our skulls got so thin.

    Another point in favor of Homo erectus as stone age pachycephalosaurs.

    Tags: 
    development
    Homo erectus

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Neandertals

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Malapa

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