The Evolution of Evolution Continued: Darwin’s Finches and Mendel’s Peas.

May 12, 2009 at 11:20 pm (Theory)
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In my recent article on Erasmus Darwin and the Evolution of Evolution, I urged that we not conflate evolution with Darwinian evolution, that we broaden our view to see that there were many fathers and grandfathers of evolutionary theory. I stand by the ideas I expressed in that post. However,  it occurred to me that, in the interests of both fairness and truth, I needed to make another post explaining just why Charles Darwin was so influential and important. Downplaying his importance was not my intention in the Erasmus Darwin article, but I believe that is how it came across.

SO WHY DARWIN AND MENDEL?

By Darwin’s day, many scientists and philosophers had already begun to imagine that organisms, and perhaps the world as a whole, evolve.* Geology had opened up the layers of the earth below for study, taxonomy got biologists thinking about the similarities between different species, philosophers were questioning Judeo-Christian accounts of Creation, and paleontology and archaeology were bringing ancient bones to the light of day.

Charles Darwin and Gregor Mendel may not have been pioneers of imagination, but they had a great edge over some of their predecessors: scientific method. Darwin did not invent the idea of evolution, and Mendel did not invent the idea of heritability, but they are the fathers of their fields because they transformed these ideas into sound scientific hypotheses and gathered observable evidence to support them. The bread and butter of science (and maybe this is just my opinion) is the pursuit of predictable outcomes. Both Darwin and Mendel were able to create models where observable circumstances led to predictable outcomes.

SOURCES AND FURTHER READING
* http://anthro.palomar.edu/evolve/evolve_1.htm <-A great outline of Pre-Darwinian evolutionary theory.

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Erasmus Darwin and the Evolution of Evolution.

May 6, 2009 at 10:56 pm (Theory)
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Charles Darwin did not exist in a historical vacuum. I have always been bothered by Darwin’s canonization in both academia and pop culture alike. “No!” I shout, “He did not invent evolution! There was no such event!” If you think Charles Darwin invented the idea of biological evolution, then you must also think Christopher Columbus was the first to assert that the Earth is round.

Little did I know, however, that one of Darwin’s predecessors in evolutionary thought was Darwin– Erasmus Darwin– his grandfather.

ABOUT ERASMUS

Erasmus Darwin’s interests were varied. He was not only a naturalist but also a poet, an inventor, a philosopher, a doctor, and a social advocate (he was a proponent of formal education for girls).

Quoting Wikipedia: “In notes dating to 1779, Darwin made a sketch of a simple liquid-fuel rocket engine, with hydrogen and oxygen tanks connected by plumbing and pumps to an elongated combustion chamber and expansion nozzle, a concept not to be seen again until one century later.”†

WORK IN NATURAL SCIENCE

Erasmus Darwin, as it turns out, did some very important writing. In the 1770′s and 1780′s, he led translations of “father of modern taxonomy” Carl Linnaeus’s botanical writings. In A System of Vegetables and The Families of Plants, he was the first to translate the Latin names of many plant species, as laid out by Linnaeus, into English.

In Zöonomia (1794-1796), Erasmus Darwin eloquently presented his theories on what would later be called evolution.

“The late Mr. David Hume, in his posthumous works, places the powers of generation much above those of our boasted reason; and adds, that reason can only make a machine, as a clock or a ship, but the power of generation makes the maker of the machine; and probably from having observed, that the greatest part of the earth had been formed out of organic recrements; as the immense beds of limestone, chalk, marble, from the shells of fish; and the extensive provinces of clay, sandstone, ironstone, coals from decomposed vegetables; all of which have been first produced by generation, or by the secretions of organic life; he concludes, that the world itself might have been generated, rather than created; that is, it might have been gradually produced from very small beginnings, increasing by the activity of its inherent principles, rather than by a sudden of evolution of the whole by the Almighty fiat.” *

… … …

“Would it be too bold to imagine that, in the great length of time since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which the great First Cause endued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions and associations, and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down these improvements by generation to its posterity, world without end!”†

THE EVOLUTION OF EVOLUTION

The quoted passages above have to be appreciated in their historical context. Lamarck did not write his famous works on the reproduction of novel traits until the early 19th century.  Gregor Mendel, often called the “father of genetics,” was only born in 1822. And Charles Darwin’s Origin of Species was not published until 1859. Even in the 1770′s, Erasmus Darwin was not the first to think about the concepts that now comprise our modern theory of evolution. In the first passage above, he cites philosopher David Hume. When we conflate evolution and (Charles) Darwinian evolution, we forget about all the perspectives and innovative ideas that shaped the discourse before and after Charles Darwin’s influential work. That is not to say he does not deserve a great deal of credit for articulating and popularizing evolutionary theory. It is important to keep in mind, though, that there were people who believed the world to be round before Columbus lived, that Columbus preceded Galileo, and that every great innovator has great-grandparents.

SOURCES AND FURTHER READING

* http://www.victorianweb.org/science/edarwin.html

† http://en.wikipedia.org/wiki/Erasmus_Darwin

http://www.strangescience.net/erasmus.htm

http://en.wikipedia.org/wiki/Carolus_Linnaeus

http://en.wikipedia.org/wiki/Jean-Baptiste_Lamarck

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Musings on Evolution and the Human Animal.

December 18, 2008 at 4:46 pm (Mammalia, Primates, Theory)
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Sometimes I ask myself, “Why am I thinking so deeply about evolutionary theory while I’m sitting on a bus on the way to my retail job? What good can it do?” But I continue regardless. Because I am hopelessly fascinated by the subject. And while it’s much more fun to think about the evolution of wings for flying or claws for digging or teeth for grooming, I often settle into more serious pondering, on the subject of evolution in modern Homo sapiens sapiens.

OR LACK THEREOF?

When I start to talk to someone new about evolution, I often get myself into an unfortunate argument–not intentionally, of course. Many perfectly intelligent people believe that as a species, human beings are no longer evolving. Immediately, to me, this notion is preposterous. And besides that, it is a sad illustration of how misunderstood, perhaps badly taught, are the key concepts of evolutionary theory.

Allow me to direct the reader to some definitions of evolution from the web. (Thank you, Google’s “define:” feature!)

EVOLUTION

  • development: a process in which something passes by degrees to a different stage (especially a more advanced or mature stage); “the development of …
  • (biology) the sequence of events involved in the evolutionary development of a species or taxonomic group of organisms
    wordnet.princeton.edu/perl/webwn
  • In biology, evolution is the process of change in the inherited traits of a population of organisms from one generation to the next. The genes that are passed on to an organism’s offspring produce the inherited traits that are the basis of evolution. en.wikipedia.org/wiki/Theory_of_evolution

Then there is the academic definition I learned in my genetics classes.

EVOLUTION IN MODERN CONTEXT

Hopefully it is apparent now that evolution is not simply survival of the fittest, even if that is a very large part of it. Evolution is a constant process. Every population, species, genus, family, and so on, is evolving as I write this. Only extinct groups don’t evolve. Even if we cure all diseases, the process of evolution will continue in our species. You can think of alleles as little genetic differences between individuals or groups of individuals. Some allele differences are readily observable, such as eye color, and some are not. When a baby is born, it contains some of its mother’s and some of its father’s genetic information, thus changing the frequency of alleles in its population. Instantly. This is a very simple illustration, and may not seem very useful in studying evolutionary change over time, but it is the unceasing births and deaths within a population that allow evolution to continue. Heritable mutations in turn add to genetic diversity.

So what is the significance of these miniscule changes in allele frequency? Remember that selection can be positive, negative, or neutral. When a completely healthy person dies without having had a child, his or her genes have been selected against. Likewise when a person with a genetic disposition toward heart disease has a child, his or her genes have been selected for. In our modern society, evolution appears to have stagnated because selection is generally neutralized by medicine and good nutrition. Genetically “fit” individuals do not always pass on their genes because they have access to birth control and do not need extra hands in the field to keep the family fed, or to take care of them in their old age. Genetically “unfit” individuals can pass on their genes because of treatments, cures, and suppression therapies.

Consider in addition the sheer size of our population and how open and fluid it is, allowing foreign genes in and sending native genes out, and you should understand why large-scale evolutionary changes aren’t occuring here. There is simply no overwhelming push one way or another.

EVOLUTION YOU CAN SEE

Hundreds of years ago, people lived shorter lives, and generally didn’t grow as tall as we do today. Whether that is proof of genetic change, or just of better medicine and improved diet, is up for debate. Evidence of large-scale evolutionary change in modern humans since history began is scant to invisible. But evolution is not all about large-scale change. In humans, the process is probably just too slow to observe.

In my mind, there are three major reasons why evolutionary change can happen quickly or very gradually within a population:

1. Population size. In order for change to sweep over the population quickly, it needs to be very small.

2. K or r selected. In a species where offspring are plentiful and reproduce soon after birth (r-selected, i.e. rats), generation times are short, and change can happen rapidly. In a species where individuals invest in small numbers of long-lived offspring (K-selected, i.e. humans), generation times are long, and change happens slowly.

3. Environmental pressure. This is where human evolution is somewhat unique.

SOCIAL VS. BIOLOGICAL EVOLUTION

There is a prevailing idea that humans now evolve socially, rather than biologically. Hopefully at this point in my article I no longer need to argue on the latter clause; we are still evolving biologically. But the former needs addressing. As a species, we use our brains (themselves a product of evolution that began longer ago than we can fathom) to solve problems. Innovations and improvements are passed from generation to generation along with genetic data. The result is that when environmental pressures become intense, a biological coping mechanism is not always necessary.

Social evolution is not constrained in the same ways that biological evolution is, and so it can occur faster and thus more noticeably. With television, radio, and the Internet, an innovation from one corner of the globe can reach billions of people at an unprecedented speed. However, humans are not the only animals that can evolve socially. Other apes are capable of innovation and teaching, as are elephants, dolphins, and who knows what else. Social evolution can reduce the significance of biological evolution, but it cannot cause it to cease.

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