Biogeography: Evidence for Evolution (Part 6)

The first time I heard about biogeography, it sounded like a pretty convincing argument for evolution. My first-year biology textbook even included biogeography under the heading, “Evolution is supported by an overwhelming amount of scientific evidence.”1 But what is biogeography, exactly? “Bio” refers to living things, so biogeography studies where different life forms are found around the world. As another of my textbooks insisted,

Suffice it to say that the distribution of many taxa [or categories of living things] makes no sense unless they have arisen from common ancestors. For example, many taxa, such as marsupials, are distributed across the southern continents, which is easily understood if they arose from common ancestors that were distributed across the single southern landmass that began to fragment in the Mesozoic.2

The idea goes, once upon ~200 million years ago, a supercontinent called Pangea began breaking into several continents.3 As those continents drifted apart, they carried the ancestors of modern organisms with them. So, the distribution of species we see today supposedly reflects their evolutionary histories.

Textbooks raise various biogeography arguments as supposed evidence for evolution, with specific examples addressed in other articles.4 For now, let’s think through how to process biogeography arguments more generally with Critical Thinking Checks 1 and 6.

Check Scripture5

It’s no secret that Genesis 1 implies God created living things to reproduce according to their kinds. So, the assumption that different kinds of animals evolved in different locations contradicts a clear teaching from Scripture. However, we could biblically expect to see a great deal of variation within kinds, including different species separating out in response to their fallen planet’s changing environments. Like other articles document, though, this process does not produce new kinds of living things.

A few chapters later, Genesis also records how God reset the world through a global flood—an event which would have largely been responsible for arranging the continents we see today. Biblically, then, the dividing continents could not have carried live land animals with them, as the floodwaters eventually covered the highest mountains (Genesis 7:18-22).

Check the Interpretations

Jumping6 to Check #6, Check the Interpretations, we can apply the usual five steps to separate fact from assumption in biogeography arguments.

1. Identify the observational science.

   When it comes to biogeography, what are the facts we’re observing in the present? Easy. We’re looking at the modern distribution of fossil or living organisms, like marsupials. We might even observe new species emerging in certain locations, but again, speciation within created kinds is quite consistent with a biblical worldview.

2. Identify the historical science.

   What story do textbooks construct about the past, based on biogeographical facts in the present? The evolutionary interpretation is that living things’ distributions reflect their evolutionary histories; for example, we mainly see marsupials on southern continents because that’s supposedly where they evolved.7 Similarly, claims that the continents began separating ~200 million years ago is a historical science interpretation, even if it’s stated as fact in textbooks.

3. Identify the assumptions.

   What do these interpretations from historical science assume? For starters, they’re assuming that earth is millions of years old and that one kind of creature can evolve into another. Mechanisms proposed to drive evolution, including mutations and natural selection, don’t account for the changes required to evolve all living organisms from a few common ancestors, as even some evolutionists recognize.

4. Identify alternative explanations.

   How could we interpret the observational facts of biogeography through a biblical lens? Biblically, we’d interpret the distribution of most fossils to represent the way animals were buried during the global flood.8 Living things’ current distributions, meanwhile, would reflect the dispersion, migration, speciation and (in some cases) later extinction of organisms which survived the flood.

   Creationists suggest different models for how living things repopulated the world after the flood. For example, organisms could have migrated across land bridges that the post-flood Ice Age likely exposed, been transported by humans, or been carried by floating rafts of logs and vegetation ripped up by the flood.

   Even evolutionists have proposed rafts to explain some organisms’ biogeography.9 One secular paper lists 15 cases where biogeography patterns that don’t otherwise make sense can be explained by “oceanic dispersal.”10 And a creationist model examining how sea currents could have carried log rafts showed a better than 90% fit with animal distributions observed today.11

5. Identify the rest of the story.

   On that note, another part of Check 6 is remembering there’s often more to the story than textbooks cover. So, let’s ask, “What other facts from observational science support a biblical interpretation?” In this case, floating log rafts could help make sense of not only coal deposits but also of marine organisms fossilized in tree amber.12 Sea creatures and trees don’t normally mix, but a global flood could explain that.

Space for Speculation

As you’ve probably noticed, biogeographical arguments tend to rely heavily on historical science because we can’t directly observe the past events which resulted in living things’ distributions today. So, as biologist Dr. Nathaniel Jeanson has pointed out, “Currently, neither the creationist position nor the evolutionary model has a consistent, comprehensive, discipline-wide explanation for biogeography.”13

Dr. Andrew Fabich concurs,

Dispersal of macroorganisms to unique ecosystems is a difficult topic for both the evolutionist and creationist alike and has been reviewed elsewhere (Statham 2010). Suffice it to say that the creationist interpretation of biogeography makes more sense out of coordinating where macroorganisms are found in the fossil record and on which continent we find macroorganisms today.14

Biblically based models of how living things spread around the earth following the flood may continue to change as observational science unveils more facts. But God’s Word does not change—including the truth of the Genesis flood, established by God’s eyewitness testimony and collaborated by observational facts. And when it comes to biogeography, those facts do not supply clear-cut “evidence for evolution” quite like textbooks may indicate. Instead, they pose problems requiring other explanations—like oceanic dispersal—which are consistent with a biblical worldview.