{"id":17834,"date":"2019-09-07T04:20:14","date_gmt":"2019-09-07T04:20:14","guid":{"rendered":"https:\/\/www.lifeandnews.com\/articles\/?p=17834"},"modified":"2019-09-09T00:45:06","modified_gmt":"2019-09-09T00:45:06","slug":"evolution-doesnt-proceed-in-a-straight-line-so-why-draw-it-that-way","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/evolution-doesnt-proceed-in-a-straight-line-so-why-draw-it-that-way\/","title":{"rendered":"Evolution doesn’t proceed in a straight line \u2013 so why draw it that way?"},"content":{"rendered":"

Quentin Wheeler<\/a>, State University of New York College of Environmental Science and Forestry<\/a><\/em>; Antonio G. Valdecasas<\/a>, CSIC – Consejo Superior de Investigaciones Cient\u00edficas<\/a><\/em>, and Cristina C\u00e1novas<\/a>, CSIC – Consejo Superior de Investigaciones Cient\u00edficas<\/a><\/em><\/p>\n

\"\"<\/a>
A high school marching band\u2019s T-shirt places a horn-playing Homo sapiens<\/em> at the end of the evolutionary process.<\/span>
\nBrian Kloppenburg, Jordan Summers, Main Street Logo<\/span><\/span><\/figcaption><\/figure>\n

Evolution doesn\u2019t follow a preordained, straight path. Yet images abound that suggest otherwise. From museum displays to editorial cartoons, evolution is depicted as a linear progression from primitive to advanced.<\/p>\n

You\u2019ve certainly seen the pictures of a chimpanzee gradually straightening up and progressing through various hominids all the way to a modern human being. Yes, they can be humorous. But these kinds of popular representations about evolution get it all wrong.<\/p>\n

As<\/a> three<\/a> scholars<\/a> of biodiversity and biology, these images bother us because they misrepresent how the process of evolution really works \u2013 and run the risk of reinforcing the public\u2019s misconceptions.<\/p>\n

Climbing a ladder to perfection<\/h2>\n

This misunderstanding is a holdover from before 1859, the year Charles Darwin first published his scientific theory of evolution via natural selection.<\/p>\n

\"\"<\/a>
The scala naturae presents a hierarchy of creation.<\/span>
\nRetorica Christiana, Didacus Valdes, 1579<\/span><\/span><\/figcaption><\/figure>\n

Until then, the traditional view of how the world was organized was through a \u201cprogression in perfection.\u201d This concept is explicit in the idea of the \u201cgreat chain of being,\u201d or \u201cscala naturae<\/a>\u201d in Latin: All beings on earth, animate and inanimate, could be organized according to an increasing scale of perfection from, say, mushrooms at the bottom up through lobsters and rabbits, all the way to human beings at the top.<\/p>\n

Originating with Plato and Aristotle, this view gets three main things wrong.<\/p>\n

First, it holds that nature is organized hierarchically. It is not a random assortment of beings.<\/p>\n

Secondly, it envisions two organizing criteria: things progress from simple to perfect and from primitive to modern.<\/p>\n

And thirdly, it supposes there are no intermediary stages between levels in this hierarchy. Each level is a watertight compartment of similar complexity \u2013 a barnacle and a coral reef on the same rung are equally complex. No one is halfway between two steps.<\/p>\n

In the 1960s a variation of the scala naturae conceived by Jesuit philosopher Pierre Teilhard de Chardin<\/a> became popular. His idea was that, although life is somewhat branched, there is direction in evolution<\/a>, a progression toward greater cognitive complexity and, ultimately, to identification with the divine, that is, God.<\/p>\n

Gradual changes, in every direction<\/h2>\n

At least since Darwin, though, scientists\u2019 idea of the world is organized through transitions \u2013 from inanimate molecules to life, from earlier organisms to different kinds of plants and animals, and so on. All life on Earth is the product of gradual transformations, which diversified and gave rise to the exuberance of organisms that we know today.<\/p>\n

Two transitions are of particular interest to evolutionary biologists. There\u2019s the jump from the inanimate to the animate: the origin of life. And there\u2019s the appearance of the human species from a monkey ancestor.<\/p>\n

\"\"<\/a>
Book covers are just one place you might see a riff on this evolutionary march.<\/span>
\nHowling at the Moon Press\/Amazon<\/a><\/span><\/figcaption><\/figure>\n

The most popular way to represent the emergence of human beings is as linear and progressive. You\u2019ve probably seen images, logos and political and social propaganda that draw on this representation.<\/p>\n

But none of these representations capture the dynamics of Darwin\u2019s theory. The one image he included<\/a> in his book \u201cOn the Origin of Species\u201d is a tree diagram, the branching of which is a metaphor for the way species originate, by splitting. The absence of an absolute time scale in the image is an acknowledgment that gradual change happens on timescales that vary from organism to organism based on the length of a generation.<\/p>\n

\"\"<\/a>
Forget a hierarchy \u2013 each organism alive now is the most evolved of its kind.<\/span>
\nZern Liew\/Shutterstock.com<\/a><\/span><\/figcaption><\/figure>\n

According to Darwin, all current organisms are equally evolved and are all still affected by natural selection. So, a starfish and a person, for example, are both at the forefront of the evolution of their particular building plans. And they happen to share a common ancestor that lived about 580 million years ago.<\/p>\n

Darwin\u2019s theory doesn\u2019t presuppose any special direction in evolution. It assumes gradual change and diversification. And, as evolution is still operating today, all present organisms are the most evolved of their kind.<\/p>\n

\"\"<\/a>
\u2018Man Is But A Worm\u2019 caricature of Darwin\u2019s theory in the Punch almanac for 1882.<\/span>
\nEdward Linley Sambourne<\/a><\/span><\/figcaption><\/figure>\n

An enduring misconception<\/h2>\n

Having been around nearly 2,000 years, the idea of the scala naturae did not disappear during Darwin\u2019s time. It might actually have been reinforced by something so unexpected as a cartoon. Illustrator Edward Linley Sambourne\u2019s<\/a> immensely popular caricature of evolution \u201cMan Is But a Worm,\u201d published in Punch\u2019s Almanack for 1882, combined two concepts that were never linked in Darwin\u2019s mind: gradualism and linearity.<\/p>\n

Given centuries of religious belief in a \u201cgreat chain of being,\u201d the idea of linearity was an easy sell. The iconic version of this concept is, of course, the depiction of a supposed ape-to-human \u201cprogression.\u201d Variations of all kinds have been made of this depiction, some with a humorous spirit, but most to ridicule the monkey-to-man theory.<\/p>\n

A linear depiction of evolution may, consciously or not, confirm false preconceptions about evolution, such as intelligent design \u2013 the idea that life has an intelligent creator behind it. Historians can work to unravel how such a simple caricature could have helped distort Darwin\u2019s theory. Meanwhile, science writers and educators face the challenge of explaining the gradual branching processes that explain the diversity of life.<\/p>\n

While less pithy, it might be better for the public\u2019s knowledge of science if these T-shirts and bumper stickers ditch the step by step images and use branching diagrams to make a more nuanced and correct point about evolution. Contrary to the Sambourne picture, evolution is better represented as a process producing continuous branching and divergence of populations of organisms.<\/p>\n

[ Deep knowledge, daily.<\/em> Sign up for The Conversation\u2019s newsletter<\/a>. ]\"The<\/p>\n

Quentin Wheeler<\/a>, Senior Fellow for Biodiversity Studies, State University of New York College of Environmental Science and Forestry<\/a><\/em>; Antonio G. Valdecasas<\/a>, Senior Researcher in Biodiversity at the Museo Nacional de Ciencias Naturales, CSIC – Consejo Superior de Investigaciones Cient\u00edficas<\/a><\/em>, and Cristina C\u00e1novas<\/a>, Biologist at the Natural History Museum in Madrid, CSIC – Consejo Superior de Investigaciones Cient\u00edficas<\/a><\/em><\/p>\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Quentin Wheeler, State University of New York College of Environmental Science and Forestry; Antonio G. Valdecasas, CSIC – Consejo Superior de Investigaciones Cient\u00edficas, and Cristina C\u00e1novas, CSIC – Consejo Superior de Investigaciones Cient\u00edficas A high school marching band\u2019s T-shirt places a horn-playing Homo sapiens at the end of the evolutionary process. Brian Kloppenburg, Jordan Summers, […]<\/p>\n","protected":false},"author":44,"featured_media":17833,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3410],"tags":[2616,250,2058,14,4251,6892],"_links":{"self":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/17834"}],"collection":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/users\/44"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/comments?post=17834"}],"version-history":[{"count":2,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/17834\/revisions"}],"predecessor-version":[{"id":17848,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/posts\/17834\/revisions\/17848"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media\/17833"}],"wp:attachment":[{"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/media?parent=17834"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/categories?post=17834"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifeandnews.com\/articles\/wp-json\/wp\/v2\/tags?post=17834"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}