Why Don't We Celebrate New Species?

I have previously linked to Olivia Judson's New York Times column called "The Wild Side". Her column is always illuminating and written with an infectious enthusiasm for the incredible variety of life on our planet. It is unfailingly lucid in explaining concepts in evolutionary biology in clear and concise prose. The column today is called "All Hail the Apple Maggot" and discusses a wonderful example of how a new species gets created from an existing one (including a great little primer on the definition of species). She also reflects on why we tend to more easily focus on lamenting extinction of species as opposed to celebrating the creation of new ones.

There is an unending stream of misinformation and outright lies being churned out on the topic of evolution and natural selection (see Zakintosh's blog post on November 17th called "The CREaTIoNist" for another unfortunate example; a supposedly scientific book by the Turkish author Harun Yahya). Given the constant hostility toward this scientifically sound but revolutionary principle I always like to link to good writing on evolution for laypeople so that at least anyone reading this blog can gain access to credible writing on the subject.

The appearance of a new species is not so dramatic. The first members of a new species will typically be indistinguishable — to us — from the species they have evolved from. And while extinction has a clear final moment — the last member of a species dies — the formation of a new species does not usually happen in a single recognizable instant. Which is why we haven’t yet raised our glasses to celebrate, say, Rhagoletis pomonella, the apple maggot fly.

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The most common way to define a species is a group of individuals that breed with each other successfully. For example, dogs, despite their vastly different looks, can breed with each other, so they are are considered one species. Horses and donkeys are counted as different species because their offspring (mules and hinnies) are sterile. For individuals to be considered as belonging to separate species thus means that they are “reproductively isolated”: they can’t, won’t, or don’t breed with each other.

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I can sense your excitement. And perhaps that’s the real reason we don’t celebrate apple maggots, or any of the other new species (and there are many we know about) that are in the process of evolving. For when a new species does appear, it’s just not that different from the old species. To evolve the flamboyant differences that distinguish a swan from a duck, or a human from a chimpanzee — that takes thousands, even millions, of years.
That is what we lose with extinction.

Photograph: Rhagoletis pomonella, the apple maggot fly. (Wikimedia
Commons)

Darwinmania!

Olivia Judson is an evolutionary biologist at Imperial College London and writes an entertaining and informative online column called "The Wild Side" in the New York Times. Being a fan of all things Darwin I particularly enjoyed her column today titled "Darwinmania" that kicks off a 18 month celebration of Darwin and his ideas on July 1st, 2008 (150th anniversary of the announcement of his discovery of natural selection) leading into February 2009 (200th anniversary of Darwin's birth) and culminating in November 2009 (150th anniversary of the publication of the "Origin of Species").

Today's column also summarizes some of the well known history of the "origins" of explaining evolution and natural selection, arguably the most revolutionary scientific idea in human history. No matter how many times one reads the fascinating story of Wallace and Darwin competing to be "first to market" with this groundbreaking discovery, one can't help but reflect on the true nature of most scientific thought as a systematic and painstaking effort built on accumulated knowledge rather than "eureka" moments of isolated genius.

Some excerpts from Judson's column:

And the “Origin” changed everything. Before the “Origin,” the diversity of life could only be catalogued and described; afterwards, it could be explained and understood. Before the “Origin,” species were generally seen as fixed entities, the special creations of a deity; afterwards, they became connected together on a great family tree that stretches back, across billions of years, to the dawn of life. Perhaps most importantly, the “Origin” changed our view of ourselves. It made us as much a part of nature as hummingbirds and bumblebees (or humble-bees, as Darwin called them); we, too, acquired a family tree with a host of remarkable and distinguished ancestors.

The reason the “Origin” was so powerful, compelling and persuasive, the reason Darwin succeeded while his predecessors failed, is that in it he does not just describe how evolution by natural selection works. He presents an enormous body of evidence culled from every field of biology then known. He discusses subjects as diverse as pigeon breeding in Ancient Egypt, the rudimentary eyes of cave fish, the nest-building instincts of honeybees, the evolving size of gooseberries (they’ve been getting bigger), wingless beetles on the island of Madeira and algae in New Zealand. One moment, he’s considering fossil animals like brachiopods (which had hinged shells like clams, but with a different axis of symmetry); the next, he’s discussing the accessibility of nectar in clover flowers to different species of bee.

Update: Today (July 9th, 2008) Judson has Part II of the series celebrating Charles Darwin. An excerpt:

So, the difficulties notwithstanding, there are many reasons to tackle the “Origin.” Reasons above and beyond the fact that it is one of the most important books ever written, and central to our culture. But to me, perhaps the most important is that reading the “Origin” is a window into a mind. A rich and fertile mind, with a holistic view of nature. One that sees the interconnectedness of living beings — that cats can alter the number of flowers — long before ecology existed as a formal subject. A mind that sees the brutality of the natural world — the wasps that lay their eggs in the living bodies of caterpillars (the caterpillars are then eaten alive by the growing larvae), the stupendous death rates of most creatures — and sees that from the terrible slaughter, great beauty can arise:

"Thus, from the war of nature, from famine and death, the most exalted object of which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."