Genesis
The Evolution of Biology
by Jan Sapp
2003
My reading this month got off to kind of a slow start because I was finishing kind of a heavier text, Genesis: The Evolution of Biology by Jan Sapp, which is both a history and a historiography, a look at how others have told this same history, of the science of biology, from the Lamarck and Darwin, through Mendel, and up to the start of the 21st century.
Along the way, Sapp describes key experiments and explains the prevailing consensus that governed various eras of research. He tells us what biologists thought, and how they came to be convinced of it, again and again, as the way they understood the natural world changed over the course of about 150 years. He notes major disagreements and competing paradigms alongside times of scientific consensus, and gives a lot of attention to why biologists believed various things, and how they sought to convince one another, both with empirical evidence, and with stories told to one another about other scientists. Sapp looks at not only how scientific ideas changed, but how the reputations and the accounts shared about important scientists changed, as their role in the history of the discipline got reimagined in light of current beliefs.
Sapp divides his book into four sections, and the two longest are about Darwinian evolution and Mendelian genetics. Those were also the two sections where I was already most familiar with the popular, textbook version of the history, and so probably the sections that were easiest to read and that I felt like I got the most out of. The other two sections - about cell biology between Darwin and Mendel, and about the search for a molecular basis for genes after Mendel, plus all the discoveries that became possible once we found DNA - were more new to me, so I was introduced to a lot of ideas, but Sapp's approach makes Genesis not the ideal format for a novice learner.
Sapp gives Darwin credit for the thoroughness and quality of his research. The idea that species change over time and new species emerge due to evolution was already a hypothesis by Darwin's time. One thing he provided was a mechanism, natural selection, that would provide a reason why evolution occurs - an idea he got while thinking about Malthus. In turn, social theorists later used Darwin to justify domestic inequality and international colonialism as necessary forms of competition. Throughout the book, I was struck by how conservative (and often racist) biologists have been whenever they've talked about politics. Darwin himself was probably a Social Darwinist too.
The other thing Darwin's work provided was a lot of meticulous evidence, combining paleontology and field biology. One of the biggest changes he proposed was that the traits individual are real while 'species' are just statistical averages, as opposed to the older Aristotelian idea that each species had an set ideal form with individuals exhibiting variations due to imperfection. Darwin specifically thought that mutations that gave advantages were the main cause of speciation. By the mid-20th century, the consensus was that each species contains a lot of variation, and that geographic isolation is the main cause of the formation of new species, as each population randomly ends up with a different mix of those variant genes, which then diverge further when they can't remix by interbreeding.
Cell theory came later. It holds that cells are the basic unit of life - they're the simplest, smallest thing that can truly be said to be 'alive,' and every living thing is made up of cells. It also holds that every cell that exists came from the division of an earlier cell. (Sapp doesn't say, but it seems to me that you have to believe in evolution to accept that.) Cell biologists wondered how genetically identical cells, all born from the same egg cell, could give rise to all the differentiated tissues of the human body. For generations, they believed it was the cytoplasmic structure of the cell, not the genes in the nucleus, that was responsible for successful cell division. That was another thing I noticed - scientists arguing that their specific object of study was the single most important thing, the ultimate cause that everything else followed from.
Amazingly, to me at least, biologists theorized 'genes' as things that hold and transmit information before they knew any of the physical basis of genetics. A gene was a tiny little black box for a long time before anyone knew what it was made of or how it worked. Which reminds me, at least, of some of the black box concepts in contemporary physics, like dark matter.
Mendel is remembered as a virtual hermit, a monk who conducted experiments on pea plants and discovered dominant and recessive genes, only to be ignored at the time and forgotten until he was rediscovered much later. Sapp notes that Mendel was a Lamarckian, and though a monk, he was 'isolated' by the dominance of Darwinism, not because he was at a monastery instead of a university. And he was 'rediscovered' by two competing scientists doing lit reviews only after they'd both independently replicated Mendel's findings. Both were happy to credit the dead guy rather than let their living rival get the glory, but if I understand correctly, we'd still have the finding even if Mendel had never published at all.
The last section, about molecular biology, which uses methods borrowed from chemistry and physics to understand what's going on inside cells at the level of proteins, enzymes, and acids, including DNA and RNA. Sapp gives a chapter to the discovery of the double helix, but spends more time on the revolutionary discoveries enabled by these techniques, including figuring out how genes actually cause anything to happen, sequencing the human genome, and a whole host of discoveries made by finally expanding away from mostly studying plants and animals to paying a lot more attention to bacteria.
The study of microbial life is really fascinating to me. It was sequencing bacterial genes that revealed the existence of the archaea, extremophiles that thrive in Earth's least hospitable environments; that proved lateral gene transfer; that showed that eukaryotes came into existence when certain bacteria started living inside other cells as permanent internal symbionts, eventually becoming our mitochondria and plants' chloroplasts; and that showed the importance of bacterial and fungal symbionts in the microbiome of every multicellular organism. That last idea really was ignored! Someone thought of it in 1918, and Sapp goes on for about 2-3 pages showing all the times someone else reconsidered the hypothesis and dismissed it, only for it to become orthodoxy 80 years later.
I feel like I've had a good overview of the major discoveries and successive theories of the science of biology. I also feel like this was maybe not the best way for me, a non-expert, to try learning these things. I would've gotten more out of Genesis if I were already more familiar with that history, and using Sapp to supplement and enrich my existing knowledge.
Along the way, Sapp describes key experiments and explains the prevailing consensus that governed various eras of research. He tells us what biologists thought, and how they came to be convinced of it, again and again, as the way they understood the natural world changed over the course of about 150 years. He notes major disagreements and competing paradigms alongside times of scientific consensus, and gives a lot of attention to why biologists believed various things, and how they sought to convince one another, both with empirical evidence, and with stories told to one another about other scientists. Sapp looks at not only how scientific ideas changed, but how the reputations and the accounts shared about important scientists changed, as their role in the history of the discipline got reimagined in light of current beliefs.
Sapp divides his book into four sections, and the two longest are about Darwinian evolution and Mendelian genetics. Those were also the two sections where I was already most familiar with the popular, textbook version of the history, and so probably the sections that were easiest to read and that I felt like I got the most out of. The other two sections - about cell biology between Darwin and Mendel, and about the search for a molecular basis for genes after Mendel, plus all the discoveries that became possible once we found DNA - were more new to me, so I was introduced to a lot of ideas, but Sapp's approach makes Genesis not the ideal format for a novice learner.
Sapp gives Darwin credit for the thoroughness and quality of his research. The idea that species change over time and new species emerge due to evolution was already a hypothesis by Darwin's time. One thing he provided was a mechanism, natural selection, that would provide a reason why evolution occurs - an idea he got while thinking about Malthus. In turn, social theorists later used Darwin to justify domestic inequality and international colonialism as necessary forms of competition. Throughout the book, I was struck by how conservative (and often racist) biologists have been whenever they've talked about politics. Darwin himself was probably a Social Darwinist too.
The other thing Darwin's work provided was a lot of meticulous evidence, combining paleontology and field biology. One of the biggest changes he proposed was that the traits individual are real while 'species' are just statistical averages, as opposed to the older Aristotelian idea that each species had an set ideal form with individuals exhibiting variations due to imperfection. Darwin specifically thought that mutations that gave advantages were the main cause of speciation. By the mid-20th century, the consensus was that each species contains a lot of variation, and that geographic isolation is the main cause of the formation of new species, as each population randomly ends up with a different mix of those variant genes, which then diverge further when they can't remix by interbreeding.
Cell theory came later. It holds that cells are the basic unit of life - they're the simplest, smallest thing that can truly be said to be 'alive,' and every living thing is made up of cells. It also holds that every cell that exists came from the division of an earlier cell. (Sapp doesn't say, but it seems to me that you have to believe in evolution to accept that.) Cell biologists wondered how genetically identical cells, all born from the same egg cell, could give rise to all the differentiated tissues of the human body. For generations, they believed it was the cytoplasmic structure of the cell, not the genes in the nucleus, that was responsible for successful cell division. That was another thing I noticed - scientists arguing that their specific object of study was the single most important thing, the ultimate cause that everything else followed from.
Amazingly, to me at least, biologists theorized 'genes' as things that hold and transmit information before they knew any of the physical basis of genetics. A gene was a tiny little black box for a long time before anyone knew what it was made of or how it worked. Which reminds me, at least, of some of the black box concepts in contemporary physics, like dark matter.
Mendel is remembered as a virtual hermit, a monk who conducted experiments on pea plants and discovered dominant and recessive genes, only to be ignored at the time and forgotten until he was rediscovered much later. Sapp notes that Mendel was a Lamarckian, and though a monk, he was 'isolated' by the dominance of Darwinism, not because he was at a monastery instead of a university. And he was 'rediscovered' by two competing scientists doing lit reviews only after they'd both independently replicated Mendel's findings. Both were happy to credit the dead guy rather than let their living rival get the glory, but if I understand correctly, we'd still have the finding even if Mendel had never published at all.
The last section, about molecular biology, which uses methods borrowed from chemistry and physics to understand what's going on inside cells at the level of proteins, enzymes, and acids, including DNA and RNA. Sapp gives a chapter to the discovery of the double helix, but spends more time on the revolutionary discoveries enabled by these techniques, including figuring out how genes actually cause anything to happen, sequencing the human genome, and a whole host of discoveries made by finally expanding away from mostly studying plants and animals to paying a lot more attention to bacteria.
The study of microbial life is really fascinating to me. It was sequencing bacterial genes that revealed the existence of the archaea, extremophiles that thrive in Earth's least hospitable environments; that proved lateral gene transfer; that showed that eukaryotes came into existence when certain bacteria started living inside other cells as permanent internal symbionts, eventually becoming our mitochondria and plants' chloroplasts; and that showed the importance of bacterial and fungal symbionts in the microbiome of every multicellular organism. That last idea really was ignored! Someone thought of it in 1918, and Sapp goes on for about 2-3 pages showing all the times someone else reconsidered the hypothesis and dismissed it, only for it to become orthodoxy 80 years later.
I feel like I've had a good overview of the major discoveries and successive theories of the science of biology. I also feel like this was maybe not the best way for me, a non-expert, to try learning these things. I would've gotten more out of Genesis if I were already more familiar with that history, and using Sapp to supplement and enrich my existing knowledge.
This sounds interesting! If you're interested in some really cool re-examinations of Darwinian biology, I would recommend "The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World - and Us" by the (notably queer) ornithologist Richard Prum.
ReplyDeleteI first became aware of him from a podcast, can no longer remember offhand if it was Ezra Klein or Steve Levitt, and I found him to be fascinating and brilliant.
I'm not too far into the book yet but already really enjoying it.
Have not open sourced it yet but I actually at one point was working on an Evolutionary Algorithm that applies (Prum's re-examined take on) Darwin's theory of Sexual/Aesthetic Selection, and it was able to outperform a traditional Natural Selection-based fitness function in the task I gave it.