Hello Thibault,

In higher multicellular organisms I don't think evolution can be observed in the time range of centuries. On the other hand, there is a beautiful experiment in which a particular strain of Escherichia coli, in only twenty years (ca. 31500 generations), evolved to a strain that was able consume citrate as carbon source (normal ecoli strains use glucose for this):

Blount, Zachary D., Christina Z. Borland, and Richard E. Lenski. "Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli." Proceedings of the National Academy of Sciences 105.23 (2008): 7899-7906.

So let's do a simple math with lot of assumptions, but that can anyway helps. The important thing in the experiment above I think is the number of generations, 31500 was ok for bacteria, so assume a new generation arise in humans every 20 years? then we have 31500*20 = 630000 years, which would be the time analogous to the ecoli example above to hypothetically evolve a molecular characteristic that can be considered a trait.

One should differentiate evolution of genotypes from phenotypic plasticity, because for example one can argue that current population is taller than that from centuries ago but that is not evolution perse.

Finally, as bacteria can evolve in these time range of centuries one should remember that we animals are in fact holobionts, and bacteria in our bodies outnumber our own cells by 10 to 1, but because of sizes, they constitute up to 3% of our mass (a lot anyway!). So these bacteria can in fact evolve in these ranges, and as they are part of us (holobiont definition) then this is perhaps what you can look at. This article might help:

Santiago-Rodriguez, Tasha M., et al. "Taxonomic and predicted metabolic profiles of the human gut microbiome in pre-Columbian mummies." FEMS microbiology ecology 92.11 (2016).

I hope that helps. Best regards.

Dear Thiboult

I honour your question. In fact I also think the same way to understand the future course of our evolution I had raised a similar question but got limited responses.

We can see only secular trends in physical parameters or some changes in genome sequence. But, may not be able to talk on solid data.

Hello Thibault,

In higher multicellular organisms I don't think evolution can be observed in the time range of centuries. On the other hand, there is a beautiful experiment in which a particular strain of Escherichia coli, in only twenty years (ca. 31500 generations), evolved to a strain that was able consume citrate as carbon source (normal ecoli strains use glucose for this):

Blount, Zachary D., Christina Z. Borland, and Richard E. Lenski. "Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli." Proceedings of the National Academy of Sciences 105.23 (2008): 7899-7906.

So let's do a simple math with lot of assumptions, but that can anyway helps. The important thing in the experiment above I think is the number of generations, 31500 was ok for bacteria, so assume a new generation arise in humans every 20 years? then we have 31500*20 = 630000 years, which would be the time analogous to the ecoli example above to hypothetically evolve a molecular characteristic that can be considered a trait.

One should differentiate evolution of genotypes from phenotypic plasticity, because for example one can argue that current population is taller than that from centuries ago but that is not evolution perse.

Finally, as bacteria can evolve in these time range of centuries one should remember that we animals are in fact holobionts, and bacteria in our bodies outnumber our own cells by 10 to 1, but because of sizes, they constitute up to 3% of our mass (a lot anyway!). So these bacteria can in fact evolve in these ranges, and as they are part of us (holobiont definition) then this is perhaps what you can look at. This article might help:

Santiago-Rodriguez, Tasha M., et al. "Taxonomic and predicted metabolic profiles of the human gut microbiome in pre-Columbian mummies." FEMS microbiology ecology 92.11 (2016).

I hope that helps. Best regards.

https://reich.hms.harvard.edu/publications

these are state of the art ancient DNA papers. Most of them have a section on selection studies.

You can also google for Human Accelerated Regions (HAR)

Hi Thibault ,

These two papers could also be of your interest.

Article Identifying genetic variants that affect viability in large cohorts

http://www.pnas.org/content/early/2017/12/12/1707227114

The best,

Hey,

There is one nice example of human evolution - lets say recently:

Why is giving birth painful?

You can find answer here: http://www.bbc.com/earth/story/20161221-the-real-reasons-why-childbirth-is-so-painful-and-dangerous

Cheers from Belgrade,

Jelena

Hi,

Thank you for all of your answers, I have a few comments to add:

Anek:

It is indeed challenging to have satisfying answers. Probably because ther is no such robust study on that matter yet?

Salvador:

Your statements are interesting but needs some additional informations.

You are probably right that it would be very complicated to study evolution of a species on that timescale, yet looking at genetic variants distributions could probably help to pinpoint selection processes.

I had heard of that very interesting experiment, yet I think it is not that easy to transpose it to different species, especially with species that share very old common ancestors. Indeed, it seems that species have "learned to evolve" in their own way, thus the rate of genetic events (point mutations, large scale genome rearrangements, unequal crossing over, retroposition, whole genome duplication etc.), the way it happens and the result of it can vary largely. Mechanisms that I mentioned above can be influenced by molecular and cellular tools that can differ following species.

1. Magadum S, Banerjee U, Murugan P, Gangapur D, Ravikesavan R. Gene duplication as a major force in evolution. J Genet. avr 2013;92(1):155‑61.

2. Shapiro JA. How life changes itself: the Read-Write (RW) genome. Phys Life Rev. sept 2013;10(3):287‑323.

3. Mattick JS. Has evolution learnt how to learn? EMBO Rep. juill 2009;10(7):665.

Your statement about phenotypic plasticity is absolutely correct, we must not forget it.

I take this opportunity to indicate that the 10:1 ratio is largely overestimated even though we still often hear it (even by teams working on gut bacteria). A more recent study indicates a 1.3:1 ratio, but it can vary from 0.5 to 2:1.

https://www.nature.com/news/scientists-bust-myth-that-our-bodies-have-more-bacteria-than-human-cells-1.19136

Thank you all for the papers, I will take a look at it.

The article on childbirth is really interesting and I wasn't expecting these conclusions, this is a real good example of a different way to evolve!