Apex

1st image) Cave painting made by the San people of eastern South Africa, who had lived in the Drakensberg Mountains for 20,000 years until they were killed and crowded out by colonists who arrived in the mid-16th c. 2nd image) Freddy Harteis, son of hunter Fred C. Harteis and host of the TV series "Hollywood Hunter," pictured with a chamois sheep he killed with a crossbow in New Zealand this spring.

Humans are apex predators. That we knew. But did you ever wonder why the animals we prey on have ceased to adapt the physical means to avoid being killed by us? Dr. Geerat J. Vermeij of the University of California-Davis has, and he has published his findings in a paper entitled "The Limits of Adaptation: Humans and the Predator-Prey Arms Race" in the current issue of Evolution. He lays out his thesis in the abstract:

"In the history of life, species have adapted to their consumers by evolving a wide variety of defenses. By contrast, animal species harvested in the wild by humans have not adapted structurally. Non-human predators have high failure rates at one or more stages of an attack, indicating that victim species have spatial refuges or phenotypic defenses that permit further functional improvement. A new compilation confirms that species in the wild cannot achieve immunity from human predation with structural defenses. The only remaining options are to become undesirable or to live in or escape to places where harvesting by people is curtailed. Escalation between prey defenses and predators' weapons may be restricted under human dominance to interactions involving those low-level predators that have benefited from human overexploitation of top consumers."

Our intelligence made up for the lack of big teeth, sharp claws, venomous bites, and other defenses. The artificial weapons we produced allowed us to become ever better hunters and start harvesting animals on a grand scale. The usual adaptations of prey - evolving to achieve greater speed, grow sharper teeth and horns, and form protective herds - don't seem to work against humans. Dr. Vermeij has been studying the effects of predators on evolution for more than 30 years and investigates why this is so. His main points are summarized by Matt Walker on his BBC Nature blog Wonder Monkey:

• Growing larger doesn't help. Increasing to a size larger that a predator's mouth restricts them to preying on the weak and the young, but this doesn't work against tool-wielding humans, who hunt even huge blue whales. Their growth even worked to their disadvantage, since the quantity of meat that they would yield made larger mammals juicy targets.
• Becoming toxic doesn't help. Humans have learned to remove toxins, that are often concentrated in organs such as the liver, and to avoid their ill effects.
• Other protective adaptations don't help. The ivory tusks of elephants and large claws of lobsters and crabs made them liabilities rather than serving as deterrents against human hunters.

Our ingenuity (and greed, I might add) have resulted in the extinction of many species, for instance the dodo and the Tasmanian tiger, and the overharvesting of others, such as cod and tuna. In evolutionary terms, we leave our prey with nowhere to go. They have no way to defend themselves and simply cannot respond. “Our arrival and technological history has engendered an enormous change in the evolution of most species on Earth,” says Dr. Vermeij, and that represents a cataclysmic shift, the implications of which we have barely begun to understand.

Darwin's drawers

Not to be confused with Vickie's knickers, the title here refers to a remarkable rediscovery of antique slides prepared by botanist Joseph Hooker after being collected by Charles Darwin (1809-1882). Dr. Howard Falcon-Lang, Fellow at Royal Holloway, relates, “While searching through an old cabinet, I spotted some drawers marked ‘unregistered fossil plants’. I can’t resist a mystery, so I pulled one open. What I found inside made my jaw drop! Inside the drawer were hundreds of beautiful glass slides made by polishing fossil plants into thin translucent sheets. This process allows them to be studied under the microscope. Almost the first slide I picked up was labelled ‘C. Darwin Esq.’ This turned out to be a piece of fossil wood collected by Darwin during his famous Voyage of the Beagle in 1834!” Of the 314 fossil specimens, 17 had been gathered by Darwin when he was on the Beagle (slideshow here). The Geological Survey implemented a formal registry process for acquisitions in 1848, but by that time Hooker had left for an expedition in the Himalayas. After many relocations, the collection passed out of memory. Dr. John Ludden, Executive Director of the Geological Survey, remarked, “This is quite a remarkable discovery. It really makes one wonder what else might be hiding in our collections.”

This is only the latest reappearance of specimens collected by Darwin. In 2009 - the 200th anniversary of his birth - the only egg from the voyage on the H.M.S. Beagle was rediscovered by 80-year-old volunteer Liz Wetton while cataloging and reboxing the bird egg collection at Cambridge University's Zoology Museum (photos here). Wetton described, "It was an exhilarating experience. After working on the egg collections for 10 years this was a tremendous thing to happen. I've been moving the egg collection from the Victorian drawers into new boxes and when this one said 'C. Darwin' I thought it may be important." The find also reminds me of the painstaking documentation of a cabinet that belonged to a rival of Darwin after it was purchased at an antique shop (see Alfred Russel Wallace's cabinet and A second look at Wallace's cabinet).

ABOVE: Microscope slides from the Sir Joseph D. Hooker Collection, British Geological Survey: 1st image) Petrified conifer from near Whitby, North Yorkshire, U.K., 2nd image) Large conifer axis from Scarborough, Yorkshire, U.K., 3rd image) Stigmaria from Wolverhampton, West Midlands, U.K., 4th image) Strobili from unknown locality.

Ernst Haeckel

I felt like revisiting the famous drawing by German biologist Ernst Haeckel (1834-1919), which illustrates his theory of embryonic development--since refuted--in which "ontogeny recapitulates phylogeny." In other words, he believed that embryos evidence earlier stages of evolution during development, which would explain why human embryos have tails. I found the image I was looking for, but also a number of beautiful illustrations from his scientific monographs. And a little reading revealed that Haeckel suggested correctly, after the publication of Darwin's On the Origin of Species by Means of Natural Selection in 1859, that the first human ancestral remains would be found in the Dutch East Indies, thus spurring the discovery of Java Man (later classified as Homo erectus) by one of his students.

Ancient animals

Feeling rather old myself this morning, my thoughts ran to Harriet, a Galapagos tortoise who died in June 2006 at the Australia Zoo owned by Steve Irwin (1962-2006) and his wife. Harriet had lived an astounding 176 years, old enough to have been one of the specimens collected by Charles Darwin on the voyage of the Beagle. Although Darwin collected 3 tortoises in the Galapagos Islands, Harriet wasn't one of them, having been collected from an island that Darwin didn't visit. But the point is that her life spanned generations of human lives. Harriet was believed to have been the one of the world's oldest living creatures.

To round things out, I have included photos of Darwin, Harriet, an unnamed tortoise being ridden at the Zurich Zoo, and a giant leatherback tortoise that came onshore to lay her eggs. Like elephants, tortoises maintain their dignity and command respect, despite their cumbersome bodies.