There has been much ado about the new BioLogos website during the past week (see here and here), and most of it has focused on the site’s aim of reconciling science and Christian theology. What irked me more, however, was the lazy way in which the creators of the site approached evolutionary science. The section on the fossil record provides a perfect example.
The evolution of whales has been a hot topic lately, and for good reason. After over a century of frustrating uncertainly we now have a very detailed (although not yet complete) understanding of how whales walked into the seas. (See here, here, here, here,and here for some of my essays on whale evolution.) Where they previously were an evolutionary enigma whales are now often presented as stunning examples of evolutionary change. Unfortunately the BioLogos site drops the ball when it comes to explaining just what we know. Their description of whale evolution reads as follows;
Fossillized whales provide yet another example of gradual change from one species to another. Whales live in the water, but they are also mammals. Although land animals are believed to have evolved from water animals, whales are thought to have evolved from land animals at a later time.
Recently, a 52-million-year-old whale fossil, Pakicetus, was found in Pakistan. It was clearly a small, wolf-sized whale, but it did not have the characteristic fat-pad, a structure that allows the whale’s jaw vibrations to be used for hearing. Also, its teeth were much like those of the terrestrial animals already thought to be related to whales. Scientists then found fossils of a more recent — 40 million years ago — and larger — 50 feet — whale species: Basilosaurus. Appearing later in the fossil record than Pakicetus, this whale showed less resemblance to terrestrial animals, although it still had a small but well-formed mammalian limb. Not long after the discovery of Basilosaurus, the fossil record of a new species of whales that had full length hind limbs and a tail was found. According to its age and structure, this new species, Ambulocetus, appeared to be a transition species between Pakicetus and Basilosaurus. More and more fossils continue to surface in this region of Pakistan, which further illustrate the gradual change from land animals to whales.
First, no self-respecting paleontologist “believes” that “land creatures” evolved from “sea creatures.” There is a slew of evidence which illustrates the evolution of early tetrapods, some of it reviewed just paragraphs before on the BioLogos page, so I do not know why they have opted for tentative-sounding language here. I would love to see people stop professing their “belief in evolution”, but I doubt that day will ever come.
More to the point, though, is that the explanation of what we have come to understand about whale evolution is absolutely atrocious. What most immediately jumps out at me is the assertion that Basilosaurus was discovered AFTER Pakicetus. Yeah, right. Basilosaurus was named 147 years before Pakicetus and its status as a transitional form has long been debated. Many naturalists thought that it pointed to a terrestrial ancestry for whales, but whether that ancestry was among carnivorans, ungulates, or some other group was up for debate. At the time of its discovery, then, Pakicetus provided an appropriate transitional form between the terrestrial mesonychids (a group of hoofed carnivorous mammals whales were thought to have evolved from at the time) and fully aquatic whales like Basilosaurus, Dorudon, and Protocetus. (It is now known that whales evolved from even-toed ungulates called artiodactyls, and themselves are highly-derived aquatic artiodactyls).
I also find it strange that the author of this section restricts the transitional series to Pakicetus, Ambulocetus, and Basilosaurus. It might be a little overwhelming trying to mention every relevant genus in what is supposed to be a short primer, but this section essentially ignores everything we have learned about whale evolution in the last 13 years. We are assured that more discoveries are being made in Pakistan but no details are provided. I would have thought that Rodhocetus would have at least merited a mention.
The entry also seems to give the impression that Pakicetus was a direct ancestor of Ambulocetus which was a direct ancestor of Basilosaurus. This is a misleading and gross oversimplification. Each of these genera represents a different period of whale evolution, and each shows differing degrees of specialization to life in the water. The fossil record is not complete enough to show whether or not any are direct ancestors or descendants to each other. They are extremely important to understand whale evolution but paleontologists have (thankfully) largely given up trying to shove transitional forms into direct ancestor-descendant relationships when no such relationship can be scientifically supported. If you want to find species-to-species transitions in the fossil record you are better off looking at invertebrates like foraminiferans.
The Pakicetus -> Ambulocetus -> Basilosaurus trajectory also ignores the branching pattern of whale evolution. (Perhaps this is not surprising in that the creators of the website clearly have sympathy for a teleological kind of evolution that is progressive towards some kind of humanoid.) It was not a straight line from terrestrial to aquatic and as surprising as it may seem there was once a diversity of strange, semi-aquatic whales. Remingtonocetids, like Kutchicetus, lived at the same time as other early whales but represent a side branch that ultimately went extinct. While early whale fossils are all important to understanding the evolution of whales not all early whales are ancestors of modern forms. This important distinction is not made on the BioLogos site.
This is the kind of slipshod science communication that has driven me to write my own book about evolution and the fossil record. I am tired of authors disrespecting readers by failing to sufficiently verse themselves in the science they are discussing. Reading a few popular summaries in Scientific American or National Geographic should not be the whole of research undertaken for someone who wants to popularize science. (Doing so is just regurgitating increasingly unsatisfying bits of a bigger story.) How are we ever going to help the public understand evolution if we hide the details from them and simply assert that everything is clear now? It is foolish to keep doing this, yet it apparently it is easier to be lazy.
Post-script: Are well-known scientists always the best science communicators? Lately I have been disappointed by the efforts of respected scientists to explain evolution, and the fossil record in particular, to the public. Since they are already established, though, when they release a new book or article people pat them on the back and say what a good job they have done. Scientists who want to reach out to the public should be encouraged, but I find it strange when I put more time and work into explaining what we know about evolutionary transitions than some professional scientists who want to explain the same subjects. Perhaps it is good that I am a no-name with a lot of prove; I just hope I don’t get lazy once I get a few books behind me!