john hawks weblog

paleoanthropology, genetics and evolution

Sima de los Huesos

  • Anthropology 105, lecture 8: Ears

    Tue, 2012-03-06 08:17 -- John Hawks
    Synopsis: 
    The auditory system reveals some of the principles of Mendelian inheritance.

    This lecture uses the auditory system to illustrate Mendelian inheritance. First the earlobes -- a classic example in teaching laboratories, where attached earlobes and pendulous (or free) earlobes are supposed to be inherited as a Mendelian character. Except we now know more than a half dozen genetic markers on different chromosomes that influence earlobe form. This lays the groundwork for a discussion of what Mendel accomplished with his experiments, and the exceedingly rare conditions that allowed him to study dominant and recessive traits. Deafness is a true Mendelian character in many families, but like other genetic conditions we've seen, it's caused by different genes in different families.

    The genetic pathway uncovered by the study of deafness allows us to investigate the evolution of hearing on the human lineage. Some fossil evidence is also relevant to this question, and I briefly introduce the site of Sima de los Huesos, where micro-CT study of the middle ear suggests the appearance of a human-like auditory capacity.

    Study questions: 
    • Other features of human anatomy, such as the curvature of the thumb when flexed backward (hitchhiker's thumb) have been proposed to be inherited in a Mendelian fashion. What genetic factors impact this hypothesis?
    • Before micro-CT scanning made it possible to study the middle ear bones of ancient people, what other evidence might have been relevant to the evolution of the auditory system?
    • How important is hearing to human survival and reproduction?
    Study terms: 
    Mendelian
    Atapuerca
    Sima de los Huesos
    Tags: 
    Mendelian disorders
    Gregor Mendel
    history of biology
    hearing

  • Meet Homo heidelbergensis

    Tue, 2011-11-15 08:28 -- John Hawks
    Synopsis: 
    The Mauer mandible is the type specimen of Homo heidelbergensis

    The Mauer mandible comes from just southeast of Heidelberg, Germany, and was found in ancient sands deposited just more than 600,000 years ago. Upon its description, the mandible was attributed to a new species, Homo heidelbergensis.

    Through the years, anthropologists considered H. heidelbergensis to be a more primitive species than Neandertals, very different from recent humans. Many anthropologists attribute other remains from the European Middle Pleistocene to this species. Probably the most important sample would be the Sima de los Huesos remains from Spain, but other crania and skeletal elements from sites across Europe have been put into the species. A few anthropologists would also include specimens from other parts of the world.

    Other anthropologists disagree. They believe that Mauer is an early member of the same population that includes Neandertals. Others would go further, noting the evidence that Neandertals are part of the ancestry of modern humans, and put Mauer into our species, Homo sapiens.

    This station has several mandibles for you to compare with Mauer, including some Neandertals, modern humans, and Homo erectus individuals.

    What to do: Compare the morphology of the Neandertal and Mauer mandibles to the modern humans. What features differ?

    Consider what you know about earlier hominid mandibles (or compare one at the station). Do you think Mauer is a possible ancestor of Neandertals? What about an ancestor of modern humans? Does it have mostly primitive dental features, or does it share derived features with one or the other?

    Study terms: 
    Mauer
    Homo heidelbergensis
    Neandertal
    Sima de los Huesos
    Tags: 
    Anthropology 105
    laboratory
    explainer
    Germany
    Mauer
    Europe
    Middle Pleistocene
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Neandertals

For years, I've worked on their bones. Now I'm working on their genes. Read more about the science studying these ancient people.

Denisova

From a finger bone of an ancient human came the record of a completely unexpected population. My lab is working on the science of the Denisova genome.

Acceleration

The advent of agriculture caused natural selection to speed up greatly in humans. We're uncovering some of the ways that populations have rapidly changed during the last 10,000 years.

Malapa

Just outside Johannesburg, the Malapa site is producing some of the most exciting finds in human evolution. This site is the headquarters of the Malapa Soft Tissue Project.