Don Simborg, MD – Brain Blogger http://brainblogger.com Health and Science Blog Covering Brain Topics Mon, 08 Jan 2018 16:30:41 +0000 en-US hourly 1 https://wordpress.org/?v=4.9.1 Lamarckian Evolution is Making a Comeback http://brainblogger.com/2018/01/08/lamarckian-evolution-is-making-a-comeback/ http://brainblogger.com/2018/01/08/lamarckian-evolution-is-making-a-comeback/#respond Mon, 08 Jan 2018 16:30:41 +0000 http://brainblogger.com/?p=23314 When scientists see the term “Lamarckian evolution”, the usual reaction is that it references a long-debunked theory. But that might be changing.

Lamarck was an accomplished biologist living in the late 18th and early 19th centuries. He was an expert on the taxonomy of invertebrates and was widely regarded as a botanist. He also wrote about physics, chemistry, and meteorology.

He is best remembered for his publication of Philosophie Zoologique in 1809 in which he lays out his theory of evolution. He describes two laws of nature. The first is that animals develop or lose physical traits depending on usage of those traits. For example, giraffes got their long necks because they constantly stretched to reach high leaves in trees during their lifetime. The second law states that these acquired changes during a lifetime are passed on to offspring, i.e., inherited. These two laws explain how species evolve by continual adaptation to their environment and eventually branch off into new species once the changes become large enough—so-called Lamarckian evolution.

There were other interesting aspects of his theories. He believed that there was some natural force that drove organisms toward increased complexity that was set apart from the usage law. The wide variety of organisms found in nature was because different life forms appeared spontaneously at different times.  Thus they do not all evolve from a common ancestor.  When gaps seemed to appear in the fossil record in certain lineages, he attributed that to a failure in finding all the relevant fossils. His theory clearly assumed gradual and continual evolution, but that evolution was always driven toward greater complexity.

Lamarckian evolution was largely debunked when the works of Gregor Mendel and others later demonstrated that inheritance occurred according to discreet rules of dominant and recessive inheritance rather than through acquired characteristics. Further discoveries in genetics during the 20th century further put the notion of inheritance through acquired characteristics to rest.

BUT, Lamarck has gotten a bit of a reprieve in the 21st century. By 2003, we had completed the Human Genome Project, which told us a lot about our genome and genes, but little about the epigenome. Since then, we’ve learned a lot. The epigenome refers to the 98% of our genome that does not code for proteins (what we traditionally call genes.) Instead, much of that huge portion of our genome has to do the regulation of genes, largely through the coding of various types of RNA. We have between 20,000 and 25,000 protein-coding genes.  That’s about the same number as a mouse or even a worm. And many if not most of these genes do pretty much the same thing across a wide spectrum of animals. What makes us different from a mouse or a worm is largely controlled by the epigenome.

It turns out that the epigenome responds to various factors in our environment like diet and toxins. These factors do cause changes in the epigenome during one’s lifetime, which, in turn, cause changes in the expression of various genes. The epigenome does not ever change the DNA sequence of a gene.  The remarkable fact is that some of the epigenomic changes acquired during a lifetime are passed on to progeny through the sperm and egg! Although it is not through the usage of parts of the body as Lamarck proposed, there is evidence of inheritance of traits acquired during a lifetime. One could call that Lamarckian.

Another way that acquired traits could be passed on to progeny in the future will be through germline genetic engineering when and if that becomes acceptable. So perhaps Lamarck was more prescient than we give him credit for.

Lamarck was extremely accomplished and well ahead of his time. He lived long before we understood genetics and his evolutionary theories preceded those of Darwin. To some extent, he has been given a bit of a bum rap. He got some things right and some things wrong. You can say that about a lot of our great scientists. He did recognize that something changes in an individual through generations and those changes interacted with the environment. Darwin also theorized that individuals change from generation to generation. Neither understood that these changes first require random genetic changes. Both knew that the environment played a large role in evolution, although Darwin’s natural selection is what is generally accepted today as the driving environmental force rather than usage of body components. He was wrong about the multiple spontaneous emergencies of different life forms at different times, but he was correct about any apparent gaps in evolutionary lines reflecting an incomplete fossil record.

Let’s give Jean-Baptiste Lamarck his due.

Reference

Carey, N. (2012). The Epigenetics Revolution: How Modern Biology Is Rewriting Our Understanding of Genetics, Disease, and Inheritance (1st ed.). Columbia University Press.

Image via Sponchia/Pixabay.

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Do Today’s Technological Advances Threaten Our Species? http://brainblogger.com/2017/12/18/do-todays-technological-advances-threaten-our-species/ http://brainblogger.com/2017/12/18/do-todays-technological-advances-threaten-our-species/#respond Mon, 18 Dec 2017 16:30:21 +0000 http://brainblogger.com/?p=23145 A lot of public back-and-forth banter has been going on lately between two giant tech personalities: Elon Musk and Mark Zuckerberg. Their public debate centers on whether or not artificial intelligence (AI) represents an existential threat to humanity.

For example, Elon Musk, when speaking at the National Governors Association in July said:

AI is a fundamental existential risk for human civilization, and I don’t think people fully appreciate that…It’s the greatest risk we face as a civilization [that will cause World War III]

Mark Zuckerberg on the other hand, touts the benefits of AI and says that Elon Musk’s doomsday predictions about AI are “pretty irresponsible.”

This prompted Elon Musk to fire back that Mark Zuckerberg’s understanding of AI is “pretty limited.”

So who is right? Only time will tell of course, but by my science-based speculation, I would say the evidence favors Musk. And greater brains than my own are telling us that artificial intelligence could be the end of Homo sapiens or any other Homo that follows, including Bill Joy, Stephen Hawking, Vernor Vinge, Shane Legg, Stuart Russell, Max Tegmark, Nick Bostrom, James Barrat, Michael Anissimov, and Irving Good. Brilliant minds, Nobel Prize winners, renowned inventors, and IT pioneers are all on record giving us warnings.

Of course other existential threats to Homo sapiens are possible and could come in the form of another bolide impact like the one that doomed the dinosaurs 66 million years ago or a supervolcano leading to extreme global weather events, a phenomena that also affected early species. Unlike the relentless human pursuit of technologies that could alter, if not eliminate, our species, these threats are essentially out of our control.

Genetic engineering, especially if aided by AI, could lead to the future speciation of Homo sapiens and pose yet another existential threat. Lee Silvers, in his book Remaking Eden, envisions a future society practicing an extreme form of behavioral isolation based on genetic engineering. In this society, only a small portion of the population, which he calls the GenRich, have the financial means to genetically enhance their children.

Over decades, the GenRich use genetic engineering techniques to optimize a variety of human traits—such as intelligence, athletic skill, physical appearance, and creativity—that give them a controlling position in society. Over time, cultural disparity between this GenRich minority population and the remaining “naturals” becomes so great that there’s little interbreeding between the two groups. Such a scenario could lead to the genetic development of a postzygotic reproductive barrier.

In other words, genetic engineering could eventually lead to a new species of humans. Once this occurs, the long-term results are unpredictable. This new species—I call it Homo nouveau—like the GenRich, may not be an existential threat, at least in the early centuries or millennia.

It’s uncertain what could happen when two human species try to coexist. We know things didn’t work out very well for the Neanderthals after Homo sapiens arrived. In fact, the same is true for Homo heidelbergensisHomo erectus, Homo denisova, and every other Homo species that may have coexisted with Homo sapiens.

In considering all the possible existential threats to us humans, genetic engineering is a possibility in the not too distant future—say in the next two to four centuries. However, if Elon Musk is right AI could supersede that in one or two centuries if we’re unsuccessful in controlling it. Then again, at any time we could be hit by a bolide. None of this bodes well for us.

References

L. Grossman, “2045: The Year Man Becomes Immortal”, Time Magazine, February 10, 2011. Access here.

Hawking, S., Tegmark, T., Russell, S. (2017). Transcending Complacency on Superintelligent Machines. Huffington Post. Access here.

Bostrom, N. Superintelligence: Paths, Danger, Strategies, Oxford: Oxford University Press, 2014.

F. Heylighen, “Return to Eden? Promises and Perils on the Road to Global Superintelligence,” in The End of the Beginning: Life, Society and Economy on the Brink of the Singularity, Ben and Ted Goerzel, eds., Humanity + Press, 2015.

Image via frolicsomepl/Pixabay.

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