Lamarckism: Dead but Useful

Posted on May 11, 2012 in Darwin and Evolution, Early Man, Human Body, Philosophy of Science

Lamarck’s theory of evolution was supposed to have died in 1859 when Darwin published his theory of natural selection.  Despite textbook depictions of Lamarckism as obsolete, Lamarckian language still surfaces from time to time, even in prestigious journals.

A recent example of speaking like a Lamarckian was detected in Science this month (4 May 2012: Vol. 336 no. 6081 pp. 538–539, DOI: 10.1126/science.336.6081.538-b) in an article entitled, “How the Modern Body Shaped Up.”  Evolutionists are not supposed to speak in terms of “use and disuse” and “inheritance of acquired characteristics,” but reporting on a meeting of the American Association of Physical Anthropologists, correspondent Ann Gibbons came pretty close: “A remarkably comprehensive analysis of more than 2000 European skeletons presented at the meeting reveals how cultural changes have altered our physiques,” she said.

In all fairness, she could have been speaking of how random mutations that were naturally selected led to better adapted physiques – and undoubtedly, if questioned, she would affirm that.  Yet for the anthropologists she quoted, it seemed too tempting to speak of humans acquiring their physiques by Lamarckian pressures:

Modern humans have gone through a lot of changes in the past 30,000 years. We switched from hunting and gathering to farming and herding; from life as nomads to settling in urban centers; from eating meat, nuts, and tubers to consuming grains, sugars, and dairy products. Now, a remarkably comprehensive analysis of more than 2000 European skeletons presented at the meeting reveals how these cultural changes have altered our physiques. “When you become a modern human, what happens to your body?” asked paleoanthropologist Christopher Ruff of Johns Hopkins University in Baltimore, Maryland, co-chair of the session on skeletal adaptation in recent Europeans.

If “cultural changes” to anatomy are not Lamarckian, what are they?  According to neo-Darwinism sensu strictu, changes due to habit have to find expression in the gametes through mutation and natural selection.  In the second paragraph, Gibbons seemed to mix Darwinian and Lamarckian mechanisms:

While other studies have documented a decrease in height after the transition to agriculture, this is the first systematic study of how the skeleton changed from the time modern humans spread through Europe 30,000 years ago until they were circling the globe in jets by the 1960s. In 10 posters, Ruff and his colleagues focused on how each part of the body, from the spine to leg and arm bones, evolved over time through both genetic and cultural change.

One anthropologist attributed a drop in strength of leg bones to the switch from a hunting and gathering lifestyle to the sedentary life of the farmer.  Another attributed changes in upper body strength to agriculture.  Recalling how Lamarck argued that men with strong arms from work might pass that trait on to their sons, it’s hard to get more Lamarckian than the description of how anatomical changes occurred:

Over the same 30,000-year period, upper body strength declined after the introduction of agriculture. In males, it then increased in the Medieval period, possibly due to intensive upper-body labor such as blacksmithing. One trend through time is that the right arm lost much of its asymmetric larger size compared to the left arm, perhaps due to fewer strongly lateralized activities such as spear throwing. Women show particularly symmetrical arms from the beginning of agriculture 7000 years ago to Europe’s Bronze Age, 3000 years ago. The researchers suspect that this stems from using both arms to make flour with grinding stones.

Perhaps it’s too tedious or confusing to speak in strict Darwinian terms, calling on random mutations to be selected.  For Gibbons and the anthropologists she interviewed, Lamarckian terminology – the environment or culture leading to adaptations directly – may be a tempting shortcut.  Even so, there were no disclaimers in the article, despite its subject of how the human body “evolved over time.”

Another example was found on PhysOrg, where Dean Falk (University of Florida) attributed the shape of the Taung baby (a hominid fossil) as an environmental adaptation: “The persistent metopic suture is an adaptation for giving birth to babies with larger brains; is related to the shift to a rapidly growing brain after birth; and may be related to expansion in the frontal lobes.”  Mutations in the birth canal should have nothing to do with mutations in the brain.

Is it possible to invoke natural selection as a cause for Lamarckian inheritance of acquired characteristics?  Consider this odd sentence from an article on PhysOrg entitled, “Evolution may explain ‘runner’s high,’ study shows”: David Raichlen, an anthropologist at University of Arizona, said: “These results suggest that natural selection may have been motivating higher– rather than low-intensity activities in groups of mammals that evolved to engage in these types of aerobic activities.

One gets the sense sometimes that creationists understand more about evolution than evolutionists do.  Like government workers, people in power rise to their level of incompetence and become lazy.  Notice how they all hypnotize one another with the power of suggestion: “These results suggest” blah blah blah; “a rapidly growing brain… may be related” to yadda yadda yadda.  Yabba dabba doo, do the evolution one way or the other.  Just get ‘er done – but keep the wascally Darwin skeptics (those vulgar Visigoths) outside the castle walls of academia and media.

 

 

One Comment

rockyway May 11, 2012

1. If it’s the case that ‘cultural practices’ shape the human body what good is paleoanthropology? i.e. if body shape is the result not of mutation but of life style, how can you discover anything about evolution from a study of bones? How can you determine whether x is the result of evolution or of life style? (Not to mention diet.)

2. ‘One anthropologist attributed a drop in strength of leg bones to the switch from a hunting and gathering lifestyle to the sedentary life of the farmer.
– The sedentary life of a farmer? I take it this person has never done any farming. (Academics have this tendency to confuse reading books with actually knowing things.)

3. “These results suggest that natural selection may have been motivating higher– rather than low-intensity activities…“
– Motivating? Is this the Tony Robbins version of evolution?

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