Lamarckian Evolution: The Laughing Stock’s Last Laugh?

Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (who, similar to Picasso, has had his name shortened over time to simply the surname – Lamarck) had quite a proclivity for the sciences. In particular, he made major contributions to chemistry, physics, botany, and taxonomy. He is even credited for coining the term invertebrate and introducing the modern use of the word biology (Burkhardt, 2014). Ironically, in the field of biology, he is now most often remembered, not for any of the many staples of modern science that he pioneered, but rather for his erroneous theory of evolution – the so-called “giraffe theory of evolution” – now lovingly named after him as Lamarckian evolution.

Perhaps it is this undeserved stigma that has triggered the fervor of some modern-day scientists (neo-Lamarckians), who, having discovered that evolution isn’t quite like how Darwin said, are eager to unsully the name of the 18th century intellect. The Darwin versus Lamarck debate, exploding decades after either scientists had life left to protect their honor, has since been drawn into the age-old dichotomous discourse of nature versus nurture. News headlines flashed “Why everything you’ve been told about evolution is wrong” to sound the death toll of Darwinian evolution, followed soon after with “End the Hype over Epigenetics & Lamarckian Evolution” denouncing the resurgent Lamarckism, only to be succeeded by fervent entreaties for the resurrection of Lamarckism (and perhaps even Lamarck himself) the year after. Why all the clamor? Hadn’t evolution been solved years ago?

No. Far from it: we are just beginning to understanding how we came to be – just beginning to take the next major steps on a long journey of discovery that will lead us through anthropology, genetics, neuroscience, chemistry, engineering , and possibly many other disciplines until now segregated in their scientific efforts.

Lamarckism

And that journey began in 1802, when Lamarck published his famous (now also infamous) Philosophie zoologique containing, among many other things, one of the first theories of organic development (Burkhardt, 2014). The gist of the theory, collapsed across translations and years of paraphrasing, was evolution by use versus disuse. Animals, across their lifetime, work towards particular biological features in pursuit of sustenance, survival, and reproduction (Lamarck, 1802). These biological features are then passed on to progeny via genetic code and the children can either benefit directly from these new biological features or build upon them by working towards better, more suitable features for evolutionary success. The classic example is that of the giraffe, whose long necks Lamarckians would attribute to some ancestor or ancestors stretching their necks to reach higher leaves. Since generations of giraffes found it beneficial to eat higher up to avoid competition with other herbivores, they concertedly worked towards elongating their necks, resulting in each generation having longer necks until we have what we call giraffes today.

Darwinism

This theory held some sway until 1859, when Charles Darwin published his On the Origin of Species explaining the natural selection theory of evolution, which simply stated that short neck giraffes died off while giraffes that, by random mutation, got longer necks passed on their genes by virtue of being more ecologically competent. It did not take long for scientific opinion to landslide in favor of Darwin’s hypothesis and Charles Darwin was henceforth hailed as the father of evolution and his theory placed at the core of evolutionary biology, leaving Lamarck to fall into ridicule, and eventually, relative obscurity. So what brought him back? Surely it wasn’t just jokes about giraffes.

Epigenetics

One unforeseen consequence of Darwin’s popularity was that the balance in nature versus nurture was tipped quite heavily in favor of nature. While natural selection recognized the importance of the environment in determining biology, its effect was only in selecting which genetic makeups were optimal, and furthermore, its effects could only be seen on the long term – measuring in the hundreds and thousands of years.

This window was dramatically shortened by observations on color change adaptations to polluted environments, centered on the peppered moth, in the early 20th century (e.g. Huxley, 1921). But due to the short lifespans of said study subjects, it was not inconceivable that Darwinian selection had simply been expedited proportional to the ephemerality of generations.

It wasn’t until the second half of the 20th century that research manipulating the dietary makeup of mice gave nurture advocates something to root for. Agouti mice, characterized by yellow fur and obesity would typically produce offspring of the same genetic and physical appearance, but when the mother’s diet was supplemented with choline, folic acids, and other such specific nutrients, her children miraculously became normal brown mice without obesity (Wolff et al, 1998). This inexplicably immediate effect of nature on biology was named epigenetics and soon after, at the turn of the 21st century, became a major buzzword as studies of DNA-methylation spread across species, eventually including humans, with the thorough examination of the descendants of the 1944 Dutch Hunger Winter (e.g. Heijmans et al., 2008; Hughes et al., 2009; Jablonka & Lamb, 2006; Tobi et al., 2009).

Lingering Lamarckians and nurturists alike were eager to jump on this as proof against Darwin’s theory of evolution. A new branch of Lamarckism emerged – neo-Lamarckism – focusing on the idea that environmental factors can directly impact progeny and the Lamarck versus Darwin debate was successfully rekindled.

Baldwin Effect

In the height of the Lamarckism resurrection fever, the Baldwin effect, first observed by James Mark Baldwin (1896) regained a lot of attention. This effect, proposed as an amendment or addition to Darwinian evolution, accounted for behavioral changes that are passed down genetically (Castillo et al, 2006). In addition to anatomical mutations, learnings that increased survivability are also naturally selected for across generations. Its distinction from Lamarckian evolution lies in that the Baldwin effect hypothesizes passing on the ability to obtain a beneficial behavior rather than the behavior itself (Turney, 2002). Nonetheless, the Baldwin effect is now often cited as Lamarckian-like or even as the bridge between Lamarckism and Darwinism.

Lateral Gene Transfer

Horizontal, or Lateral, Gene Transfer is another 20th century idea that has made strong associations with Lamarckism in the 21st century. The concept arose as a complement of vertical gene transfer –the transmission of genetic material across generations –and describes the sharing, splicing, or other means of transferring genetic material between cells of the same generation (Heard & Martienssen, 2014). This has only really be observed in bacteria, whose rapid evolution, popularized by recent concerns about the antibiotics arms race, owes to frequent recombination of nucleus and mitochondrial DNA.

The hype was upped when recent studies found that these prokaryotic (bacterial) recombinants can and are spliced into multicellular organisms. Bacterial DNA has been found in many organisms that make use of anaerobic metabolism (Keeling & Palmer, 2008), and as yet inexplicable large chunks of bacterial DNA have been found in Drosophila flies (Zhaxybayeva & Doolittle, 2011). While the evolutionary benefits and impacts of this type of horizontal sharing of genes are still unapparent, neo-Lamarckians are quick to claim them as aspects of evolution left unexplained by Darwinism. It is also a notch in the belt of nurture, the new flag Lamarckism flies under.

So Who Gets the Last Laugh?

No one. And not just because biology isn’t humorous, but because it’s high time both Darwin and Lamarck were allowed to retire. Their contributions to evolution shall be recorded in the annals of biological and psychological history, but continued division of the modern research between two camps is hardly productive. Our current understanding is that none of these neo-Lamarckian or Darwinian concepts are false, but rather that they cooperate to form a bigger picture of the environment acting upon our genes: nurture via nature (Ridley, 2004). To fully understand this new theory of evolution we need to not only merge camps, but merge disciplines – following in the footsteps of fields like neuroanthropology (Lende & Downey, 2012), which are emerging at the border of historically segregated fields to answer questions like the genetic capacity for culture and its impact on evolution.

Unfortunately then, that means that the underdog Lamarck doesn’t get to say “I told you so”. However, with luck he’ll soon be allowed to take off his dunce hat and be treated as equals with Darwin as contributors, rather than competing owners for the theory of evolution.

References

Burkhardt, R. W. (2014). Jean-Baptiste Lamarck | french biologist. InEncyclopædia Britannica. Retrieved from http://www.britannica.com/biography/Jean-Baptiste-Lamarck

Castillo, P.A., Arenas, M.G., Castellano, J.G., Merelo, J.J., Prieto, A., Rivas, V., Romero, G. (2006). Lamarckian Evolution and the Baldwin Effect in Evolutionary Neural Networks. doi: arXiv:cs/0603004

Heard, E., & Martienssen, R. A. (2014). Transgenerational epigenetic inheritance: Myths and mechanisms. Cell157(1), 95–109. doi:10.1016/j.cell.2014.02.045

Heijmans, B. T., Tobi, E. W., Stein, A. D., Putter, H., Blauw, G. J., Susser, E. S., … Lumey, L. H. (2008). Persistent epigenetic differences associated with prenatal exposure to famine in humans.Proceedings of the National Academy of Sciences105(44), 17046–17049. doi:10.1073/pnas.0806560105

Hotopp, J. C. D., Clark, M. E., Oliveira, D. C. S. G., Foster, J. M., Fischer, P., Torres, M. C. M., … Werren, J. H. (2007). Widespread lateral gene transfer from Intracellular bacteria to Multicellular Eukaryotes. Science317(5845), 1753–1756. doi:10.1126/science.1142490

Hughes, L. A. E., van den Brandt, P. A., de Bruïne, A. P., Wouters, K. A. D., Hulsmans, S., Spiertz, A., … van Engeland, M. (2009). Early life exposure to famine and Colorectal cancer risk: A role for epigenetic mechanisms. PLoS ONE4(11), e7951. doi:10.1371/journal.pone.0007951

Huxley, J. S. (1921). Some implications of the chromosome theory of heredity. Science Progress in the Twentieth Century,16(62), 235–250. doi:www.jstor.org/stable/43431523

Jablonka, E., & Lamb, M. J. (2006). The changing concept of Epigenetics. Annals of the New York Academy of Sciences981(1), 82–96. doi:10.1111/j.1749-6632.2002.tb04913.x

Keeling, P. J., & Palmer, J. D. (2008). Horizontal gene transfer in eukaryotic evolution. Nature Reviews Genetics9(8), 605–618. doi:10.1038/nrg2386

Lende, D. H., & Downey, G. (2012). The encultured brain: An introduction to neuroanthropology. Cambridge, MA: The MIT Press.

Ridley, M. (2004). The agile gene how nature turns on nurture. New York: HarperCollins Publishers.

Tobi, E. W., Lumey, L. H., Talens, R. P., Kremer, D., Putter, H., Stein, A. D., … Heijmans, B. T. (2009). DNA methylation differences after exposure to prenatal famine are common and timing- and sex-specific. Human Molecular Genetics18(21), 4046–4053. doi:10.1093/hmg/ddp353

Turney, P.D. (2002). Myths and Legends of the Baldwin Effect. Paper presented at 13th International Conference on Machine Learning: Workshop on Evolutionary Computation and Machine Learning, Bari, Italy. doi:arxiv.org/abs/cs/0212036

Wolff, G. L., Kodell, R. L., Moore, S. R., & Cooney, G. A. (1998). Maternal epigenetics and methyl supplements affect agouti gene expression in Avy/a mice. The FASEB Journal12(11), 949–957. doi:0892-6638/98/0012-0949/$02.25

Zhaxybayeva, O., & Doolittle, W. F. (2011). Lateral gene transfer.Current Biology21(7), R242–R246. doi:10.1016/j.cub.2011.01.045

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