What Lamarck’s Giraffe Got Right

0 0 5 minutes read

https://www.profitableratecpm.com/f4ffsdxe?key=39b1ebce72f3758345b2155c98e6709c

French naturalist Jean-Baptiste Lamarck proposed the first evolutionary theory of life in the early 1800s. But for centuries he was mocked and criticized by those who followed him. New findings suggest that his central claim was fundamentally right. In his latest book, Power of life: the invention of biology and the revolutionary science of Jean-Baptiste LamarckStanford historian Jessica Riskin tells the story of Lamarck’s life and work. Below are three revelations she had while writing the book.

1 The science of biology was born in a messy garden

When I started writing about Lamarck, the man who coined the term “biology“in 1802, I knew that he had lived and worked at the botanical garden in central Paris, the Garden of Plants (Garden of Plants). But I did not realize that the science of biology and its central idea of the evolution of life first took root in this garden itself, and then grew out of a fertile tangle of activities that included not only the sciences, such as botany and zoology, but also philosophy, literature, and all the arts.

In this landscape which gave birth to the first theory of evolution, I was surprised and delighted to find, for example, poetic rhapsodies on the sexual life of plants by Sébastien Vaillant, one of Lamarck’s predecessors at the royal botanical garden. The idea of a fundamental commonality and continuity between all forms of life, plants and animals, became central to Lamarck’s revolutionary theory. Equally delightful were the philosophical-poetic reflections on love and friendship between animals – within and between species – by the novelist Bernardin de Saint Pierre, who briefly served as director of the garden. His writings featured a real lion and a dog, best friends in the world, evacuated from the king’s collection at Versailles during the Revolution. Their friendship led Bernardin to speculate that interspecies love could produce new species.

The Jardin des Plantes, which I came to think of as the Garden of Evolution (a sort of counter-narrative to the Garden of Eden) also contained some wonderful scenes, including a series of concerts given for a pair of elephants who arrived at the menagerie in 1798. The Garden’s naturalists organized these concerts in order to measure the elephants’ emotional responses to different types of music and compare them to human responses. The Garden’s librarian, Georges Toscan, described these experiences in a series of literary and philosophical essays, and the elephants’ responses were also described by an illustrator who worked at the Garden, Nicolas Maréchal.

This combination of philosophy, music, art, literature, and scientific experimentation informed Lamarck’s thinking as he began to imagine a dynamic interconnectedness of all living things, including humans. He transformed this idea into the first modern theory of evolution and proposed Biology as a science of life. The idea caught on! It served as an essential foundation on which Charles Darwin could build.

2 The world is made by living beings

Lamarck made a radical decision by reallocating God’s monopoly on creation to mortal living beings. He considered that organisms constantly create and recreate not only themselves, but also the world around them. He wrote and taught that living organisms made up the inanimate world: mountains, islands, coasts. When I was writing about this idea, I wondered how close it came to current accepted science regarding the formation of structures on the Earth’s surface, such as mountains. Pretty close, it turns out!

**ADAPTABLE:** Author Jessica Riskin argues in her new book that Lamarck was right all along: animals shape their own evolution. *Photo by Jim Block.*

Through my reading and conversations with geologists and geochemists, I have discovered that people who study mineral evolution today believe that living organisms and the biochemical processes they carry out are responsible for most of Earth’s mineral species. As a mineral physicist, Robert Hazen of the Carnegie Institution, said: “The origin of life depends on minerals, but the origin of minerals depends on life.”

I knew that the White Cliffs of Dover were made of chalk from pulverized shells. But I didn’t think about the limestone that makes up many other mountain ranges – the Rockies, the Alps, the Guilin Mountains of China – and which is also made from corals and shells. I also did not realize that the free oxygen in the Earth’s atmosphere came from living organisms or that this free oxygen was essential to the mineralogy of the Earth’s surface. Apparently, biological activity could even have helped stabilize the continents by increasing the rate of granite production. Thus, Lamarck’s idea of a world created by life is consistent with current science. Realizing this transformed the way I saw the world, not just plants and animals but also the inanimate world, all as the product of living creation.

3 Lamarck’s giraffe returns

Giraffes are what most people think of when they hear the name Lamarck. Indeed, for nearly two centuries, science teachers and textbooks have cited what he said about giraffes as an example of his error. Lamarck said that when giraffes stretch to reach high branches, they extend their necks infinitely and then pass the change on to their offspring. Added over thousands of generations, these lengthenings result in the lengthening of the giraffe’s neck. Darwin adopted Lamarck’s idea, which he called “the inherited effects of use and disuse.” But after his death, a new generation of scientists modified his theory and, in their neo-Darwinist version of evolution, they banned the idea of ”inheritance of acquired characteristics”, which had become unthinkable in mainstream science.

Read more: “When We Had Lunch”

According to these neo-Darwinists, living beings were passive objects of external forces: they varied in a purely random manner and were then influenced by their environment, selected or deselected in the struggle for survival. Nothing they did – and no changes they underwent as a result – could influence the course of evolution. In other words, this neo-Darwinist theory made organisms as passive as they were according to the “design argument”, the theory that God designed and built each of them.

But recently, the study of epigenetic inheritance – including the chemical groups on or around DNA that change the way it is expressed in the body – has shown that inherited characteristics can be acquired during the next generation. I was part of a group conducting an experiment, still in its infancy, on epigenetic inheritance in giraffes, looking to see if there are epigenetic differences between two species of giraffes and between giraffes and their closest relatives, the okapis. As a historian, I don’t usually participate in scientific experiments, but I have asked friends and fellow biologists to undertake this with me, and we are working with the Giraffe Conservation Foundation in Namibia.

Furthermore, the evidence that animals are active and not passive in the evolutionary process goes well beyond the study of epigenetic inheritance. Scientists in several fields of evolutionary biology have studied the myriad ways in which animal behaviors shape the course of evolution. The last line of THEPower of life (spoiler alert!) is “Lamarck was right”. I know it’s important to be clear about what I mean when I say that someone who died in 1829 was “right” about evolution. Obviously, he knew nothing about DNA, which is at the heart of current biology, or epigenetics. But I was fascinated to learn of the ever-growing evidence that he was right that animals have evolutionary agency: through their behaviors, they help shape the course of evolution.