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Mental Gymnastics

Mental Gymnastics


There is nothing like problem solving to keep one mentally alert. Some people might say that the study of nature is a form of problem solving and so it is. Collecting information is only half the battle. The real challenge is to try to explain the data.

The vast diversity of living organisms on earth poses a great challenge to all biologists. Where did all that variety come from? There are basically two competing explanations: either separate creations, or evolution. A group of scientists met in Moscow, Idaho last June to compare notes on their research projects. The biologists at the conference approach their discipline bearing in mind that God created organisms according to their kinds (specific body plans) during the creation week. The problem however is that we do not know how large or how small the created kinds are.

Although we sometimes hear the term “fixity of species”, no biologist would defend this idea since a precise definition of species is not available. This means that the smallest group which might constitute a created kind would be at the genus level. With the genus Rattus for example, various rat species would all be within the rat kind. The idea is that some time after the creation, individual species have developed from a generalized rat body plan.

Many biologists today however suspect that the created kind may be larger still, at the family level. Rats, for example, along with mice, voles, hamsters, lemmings, muskrats and gerbils are categorized into a family of organisms with a roughly similar body plan and behaviours.

The next more inclusive clustering of organisms is at the order level. The rodent order includes tremendous variation on the rodent theme such as porcupines, squirrels, prairie dogs and marmots, beaver as well as the rats, mice and voles. Might all these creatures be descendants of one created kind? In this case a dramatic burst of change would be needed at some stage since the creation.

Obviously such questions could degenerate into useless speculation. However some biologists in Europe and in the United States have set out to test these ideas. Firstly it was necessary to establish some criteria to try to recognize members of a created kind. The term baramin was established from the ancient Hebrew word bara meaning “created” and min meaning “kind”. Initially hybridizing experiments were carried out on the premise that only members of a created kind would be able to produce offspring together. Eventually, since not all organisms are capable of sexual reproduction, the definition was broadened to include statistical analysis of many characteristics of organisms.

When a study suggests that a group of organisms exhibits basic features in common, this is said to be evidence of continuity. In this case all these organisms are provisionally assumed to represent the same monobaramin. If a conspicuous difference or discontinuity separates two groups, then each is placed in separate apobaramins or separate kinds. A holobaramin is defined both in terms of internal consistency and external gaps between it and other clusters of organisms. Thus a holobaramin is perhaps a promising approximation of a created kind.

Obviously with computer time and a data matrix the researcher is in business. Further good news is that most scientists do not need to engage in the tedious business of collecting information for a character matrix. Plenty of such data bases, representing a wide variety of organisms have already been published. All the researcher has to do is apply the equation of choice to the data, and see what kind of pattern is revealed. In this context, any topic is available for reconsideration, as, for example, the fabled organisms of the Galapagos islands.

The Galapagos archipelago is a collection of 29 or so volcanic islands of various sizes and elevations. They range in size from a few square metres up to 4700 square kilometers for Isabela. Thirteen of the islands are more than 10 square kilometres in area. The largest ones exhibit the highest elevations, up to 1700 m on Isabela. For most of the islands, the distance to the nearest island is less than 2 km. In addition, almost all of them lie less than 100 km away from the central island of Santa Cruz.

The biological communities on the islands occur in zones matching elevation. While the largest islands support the highest number of plant and animal species, it nevertheless is the case that the smaller islands exhibit a much higher proportion of endemic (unique) species. While large Isabela has 347 species of which 89 are endemics, tiny Genovesa, with only 40 species nevertheless has 19 endemics. Most of the endemics are found in the arid and transition zones rather than in the tropical highlands.

The question which all biologists seek to answer is, where did the endemic species come from? In view of the fact that these islands probably arose soon after the flood, the founding colonies of organisms probably arrived on rafts of vegetation from South America. Even today, much of the biological community is the same as on the mainland but with many fewer species.

The endemics on the other hand are similar, but not identical, to mainland species. The case of the three Galapagos mockingbird species particularly intrigued Darwin. Each species is endemic to a single island. Where did they come from? One possibility is that a single population came to the archipelago. Later, on separate islands, the populations became adapted to different environments. This process is called natural selection.

Other explanations are however possible. Three different populations may have invaded separate islands. Similar populations on the mainland perhaps later died out leaving those on the islands as the only surviving representatives. Alternatively a sizeable group arrived together but the representatives which migrated to separate islands differed slightly in their genetic characteristics. Over time further loss of some variability in the three populations caused them to become yet more different. This process is called genetic drift. Another possibility is “mediated design.” According to this idea, proposed by Dr. Todd Wood and colleagues, the arriving population had special genetic characteristics preprogrammed to be expressed after the flood as required for survival.

With all these possibilities in mind, Dr. Wood, a biologist at Bryan College in Tennessee, set out to study certain Galapagos endemics. He was not averse to the idea that unique species (endemics) developed on the Galapagos archipelago. He applied his statistical analysis to the taxonomic categories to see if the Galapagos organisms could be grouped within larger baramins or created kinds. He then looked at the endemics and their distributions. Would his statistical tools shed any light on the situation?

The simplest case is that of the Galapagos hawk. There is one endemic species which lives on nine islands. Both in appearance and in similarity of DNA sequences, this bird resembles Swainson’s hawk which migrates between the Great Plains of North America and northeastern Argentina. The Galapagos hawk, on the other hand, is extremely sedentary. It shows no inclination to fly over water, even to islands which are close by. So did a large population invade several islands and then later lose its wanderlust? It seems probable.

The famous Galapagos tortoises are a more difficult issue. All island specimens are classified in the same species. Populations occur on eleven islands and each can be distinguished on the basis of appearance and behaviour. The tortoises definitely prefer to breed with individuals from their own island. Thus many people consider each island population to be a separate subspecies.

The most conspicuous difference is in the shape of the shell (carapace). Some island populations have a domed carapace (like similar species in South America) while other local populations have a saddleback shape. Neither shape appears to confer an advantage over the other in any of these environments As far as the origin of the archipelago tortoises is concerned, whether the population arriving was large bodied or small, domed or saddlebacked, this study provides few answers.

Among bird groups, Dr. Wood considered the gannets (genus Morus) and boobies (genus Sula) of which there are three booby species present. He ran his baraminic distance analysis on a data base involving these two genera. The study revealed a clear discontinuity between the two genera. This he elected to ignore on the basis that such small created kinds would be “unprecedented in vertebrate baraminology.”

Such a result obviously will continue to be unprecedented if no one takes the results seriously. In any case these statistical studies are mere tools, not definitive indicators of relationship.

No data base exists on the archipelago’s most famous inhabitants, the thirteen endemic finch species. Nevertheless Dr. Wood concludes that the finches indeed diverged through natural selection into separate species. Each species presumably developed on a separate island and then flew to other islands. Today as many as ten species live together on the islands and no island has only one species. Amusingly in the parallel case of the daisy tree (Scalesia), eleven endemic species which occupy separate islands, Dr. Wood concludes that they diverged probably from a mainland population through drift rather than natural selection.

It is apparent that there are few clear answers. Nevertheless the important thing is that these scientists are asking questions with a Christian focus. In time we will accumulate more insights. Obviously in all areas of biology there are plenty of research topics available for creation based biologists. Many bright young researchers, such as the ones we heard last June, are stepping up to meet this challenge.

Margaret Helder
October 2005

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