Genomics at the Origins of Agriculture

Genomics at the Origins of Agriculture, Part One

The causes and consequences of the Neolithic revolution represent a fundamental problem for anthropological inquiry. Traditional archeological evidence, ethnobotanical remains, artifacts, and settlement patterns have been used to infer the transition from foraging to primary food production. Recent advances in genomics (the study of the sequence, structure, and function of the genome) has enhanced our understanding of the process of plant and animal domestication, revealed the impact that adaptation to agriculture has had on human biology, and provided clues to the pathogens and parasites thought to have emerged during the Neolithic. Genomic analysis provides insights into the complexity of the process of domestication that may not be apparent from the physical remains of bones and seeds, and allows us to measure the impact that the shift to primary food production had on the human genome. Questions related to the location and the process of domestication can be answered more fully by analyzing the genomes of the plants and animals brought under human control. The spread of the agriculture package (plants, animals, and technology) by cultural diffusion or demic expansion can also be investigated through this approach. Whether dissemination by farmers or the diffusion of farming knowledge and technology was the source of the Neolithic expansion, this process should be revealed by the patterh of genetic and linguistic diversity and language found from centers of agricultural Neolithic development. In addition, a number of pathogens that were previously thought to have been transmitted from domesticated species to human now appear to have been present in foragers long before the agricultural revolution took place. Furthermore, we now have evidence that humans were the source of the transmission of some parasites to domesticated animals. For all of these reasons, data from genomic studies are providing a more complete understanding of the origins of agriculture, a critical hallmark in human evolution.

Genomics at the Origins of Agriculture, Part Two

Agricultural expansion was such a momentous event that cultural or genetic evidence of its impact should be apparent. Abundant evidence indicates that agriculture was introduced into Europe at least 9,000 years ago. The primary issue remains whether agriculture spread by contact or by farmers moving into Europe. If agriculture was brought by farmers moving into foragers’ territory, then genetic evidence should be apparent in the genes of modern Europeans. If foragers were displaced, then European genetic profiles should reflect the source population from the Near East. If there was interbreeding with the foragers who had a distinct genetic profile, then the genes of the Europeans descendants should reflect this admixture, with a clinal distribution of traits radiating from the Near East. These scenarios have been the focus of decades of debates between anthropologists and geneticists. In addition, genomic studies have been applied to pathogens in order to explore the link between agriculture and infectious disease.

The most interesting of these is the second in my opinion, with a detailed section about diseases intoduced due to agriculture and domestication. It seems we can blame cows for TB. One thing I spotted was that malaria as a common human illness is dated to 6,00o BP, but the skeletons at Catal Hoyuk show anaemias associated with it, although I’m not sure at what date. Another interesting snippet was that you need a population of about 300,000 to maintain an endemic disease like measles.  You learn something everyday. Although worthy of mention is a quote from the Ramayana in the first one..

In the Golden Age, agriculture
was abomination. In the Silver
Age, impiety appeared in the
form of the agriculture. In the
Golden Age, people lived on
fruits and roots that were obtained
without any labour. For
the existence of sin in the form
of cultivation, the lifespan of
people became shortened

Which seems to be a pretty accurate description of what happened. It really makes you wonder why we swapped to agriculture when you read this..

Harlan demonstrated that in three weeks a family could hand strip enough wild einkorn grain to last them a year

The only real reason I can think of to abandon this kind of lifestyle is population pressure. I’ll have to look up the climate in the Euphrates/Zagros area about 12,000 to 11,000 years ago to get a better picture.

One response to “Genomics at the Origins of Agriculture

  1. In the Golden Age, agriculture
    was abomination. In the Silver
    Age, impiety appeared in the
    form of the agriculture. In the
    Golden Age, people lived on
    fruits and roots that were obtained
    without any labour. For
    the existence of sin in the form
    of cultivation, the lifespan of
    people became shortened

    Ah the golden age! (Nice quote)

    The only real reason I can think of to abandon this kind of lifestyle is population pressure.

    Maybe: when you are very succesful, population grows and eventually you are again in a difficult situation.

    But it’s also possible that agriculture and pastoralism appeared as something natural, we being a creative smart species that likes to have some control on the enviroment. Just, you’re already using this plant or animal, why not to garden it, or to adopt a cub? The evolution into farming seems just natural. And when your neighbours already have it, you eventually have little choice but to adapt or become marginal.

    Huntergatherers across the world are naturally reluctant to adopt Neolithic (in Basque famer is called “nekazari”: one whose job is effort, tiredness) but they eventually fall to it anyhow.

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