How can a population of organisms reproduce and over time become several hundred species each of which has its own menagerie of characteristics? This is a fundamental evolutionary question for which many different mechanisms have been proposed as solutions over the past 200 years. With AiG’s Ark Encounter nearing completion Ken Ham is about to put on display his – and AiGs – own understanding of how thousands of species found their origins in a small number of common ancestors. In other words, he will be more visibly promoting his alternative view of the origin of species that he has been promoting for some time. However, most lay Christians and the general public are likely not familiar with this view I have called radical accelerated diversification. Unfortunately for Ken Ham, the very Ark that he will be promoting as a Christian theme attraction presents the most compelling observational evidence that undermines his own interpretation of the origins of species.
The problem results form something called a genetic bottleneck. A genetic bottleneck occurs when the number of individuals in a population is reduced drastically. Even if this reduction in population is temporary it can have profound lasting effects on the genetic variation in a population. For example, there is quite a bit of morphological variation among domestic dogs around the world. What if the population of domestic dogs were suddenly reduced to just 20 and they were all Dalmatians? As those Dalmatians reproduce with each other to form larger and larger populations what do you think those dogs would look like? Yes, Dalmatians.
There could be a million Dalmatians 200 years later. They would have some minor variations but they would all be easily recognized as Dalmatians. The amount of genetic variation among living Dalmatians is not very great and so future generations would have little genetic variation to work with in terms of allowing them to adapt and change to their environment. Even if we wished to change them we would have little or no variations to choose from to enact any change over time. Dalmatians only represent a fraction of the genetic variation present among all dogs but much or most of that variation is lost in a bottleneck event.
Noah’s Ark – genetic bottleneck in the extreme
What would the ultimate genetic bottleneck look like? It would look like a population reduced to only a single reproductive pair that represents an entire species. Does such a bottleneck like this sound familiar? According to the young earth creationist’ interpretation of scriptures Noah’s flood bottlenecked all living land animals – and apparently plants and fungi too – in the most extreme way possible. In many cases it reduced species – and they say entire families of species – all the way down to two lone individuals. Population biologists typically get worried about a the genetic health of a species when its numbers get down into the hundreds or even thousands.* A reduction to just two would be a genetic catastrophe! Ken Ham is all about global catastrophes but this one would result in the exact opposite result of what he thinks has happened.
Below is a graphic Answers in Genesis has been using the past couple of years to illustrate their view of the origin of species. In this graphic you can see that AiG views “kinds” as diversifying into many species – each represented presumably by thousands or millions of individuals – before Noah’s flood. The Noahic Flood results in the vast majority of those pre-Flood species going extinct and only a single lineage represented by a single pair of animals is preserved on Noah’s ark. That pair of common ancestors then represents the ancestral stock from which all subsequent species must evolve – yes this is evolution.
Ken Ham suggests that all 37 living feline species and 100+ extinct species with their incredible range of features and adaptations were derived from just a single pair of common ancestors? That variation we see today in felines and the extinct relatives is the results of hundreds of millions of differences in their genomes. Where did this variation come from?
The YEC genetics mantra is that God created “kinds” with huge amounts of variation and that all that evolution mechanisms natural selection does is sort out that front-loaded variation.
Ken Ham tweeted the following today (3/30/2016) in regards to his view of evolution: Some think natural selection is the same thing as evolution. No. Natural selection works in the exact opposite direction of evolution.
He is not wrong in the sense that strong negative or positive natural selection acts to reduce genetic variation because it eliminates alleles from a population over time. But of course for natural selection to work there must be heritable genetic variation in a population to begin with. We have observational scientific evidence that species that have been reduced to small population sizes lose their genetic variation and become essentially clones of one another. As a result, these populations cannot evolve by natural selection or genetic drift and thus will not change until they have replenished their genetic variation. As long as genetic variation is absent, they do not, and cannot, evolve.
For example, all the cheetahs alive in the world today are nearly genetically identical to each other because that species was bottle necked in the past. Hundreds of generations later they still haven’t recovered much genetic variation which is only possible via new mutations. If Ken Ham’s rapid evolution model were correct every species on earth should be as genetically restricted as the cheetahs are but this is not what we observe. Instead we find that species have a bounty of genetic variation. Most feline species are more variable than humans and then you have to consider how different species of felines are from one another.
Noah’s ark is the ultimate population, and even species, bottleneck which would have eliminated the vast majority of genetic diversity in all kinds. After departing the Ark these kinds would have been incapable of evolving or diversifying or becoming genetically sorted or whatever term Ken Ham wants to use. They would look virtually identical today to the way they looked the day they stepped off the Ark. BTW, this is what we observe. All the animals described in the Bible look and act today they way they are described in the Bible. They have not changed dramatically as the YEC model predicts. Where is their observational evidence that they claim is the only form of real science? I will provide observational evidence that species have not fundamentally changed over the last 4000 years in my next post.
Noah’s ark results in a massive loss of genetic information. Ken Ham likes to say that all species are losing information over time but he never mentions the single greatest event of massive information loss in earth’s history. He would find that evolutionists would completely agree with him that if all animals were restricted to a bottleneck only 4500 years ago then that would truly represent a serious loss of information during that time. But as I just indicated, Ken Ham can’t afford such a massive loss of information at this time. He desperately needs exactly the opposite. He needs that bottlenecked pair to have the most variation of any pair of animals in the history of the world for his hyper-evolution by natural selection to have any hope of working.
Look at it from the perspective of a gene (more on this in a future post). If there were 200 different forms of a particular gene in the members of a “kind” before the flood how many of those variants could there have been on the Ark? Not many. Each parent could have had two versions at most because animals all have just two copies of their genes. Add to this the problem that genetic sorting had been going on for 2000 years before the flood and so no two individuals are going to have anywhere close to a high percentage of the original created variation.
How can YECs rescue themselves from this population genetics nightmare? I really don’t know because I have found hardly a mention of this problem in the YEC literature. But there is one hand-wavy explanation that I have been given when I pose this question in person. It has been suggested that there was a special preservation of genetic variation by God in the two animals he brought to the ark. God performed some sort of supernatural direction of a male and female that represented the two most extreme genetic versions of the “kind” being directed to come to the ark thus preserving some – but still only a small fraction – of the original variation of the “kind” on the ark.
This solution is no solution as you will see in my next post where we will look at some specific examples but for now I want to point out a very practical way that AiG has not thought this through and seems unaware of how profoundly problematic their hyper-evolution hypothesis is. And that is all that it is, a hypothesis.
Answers in Genesis is producing animals for their Ark Encounter that supposedly demonstrate what those common ancestor of today’s species may have looked like in Noah’s day. And what did they look like? They looked like a mixture of today’s species but they also are portraying the male and female as very similar to each other as if they are the same species. But if God directed the most genetically diverse pair of animals onto the ark the males and females of every kind should look as different from one another as possible rather than the same as they are being portrayed. For example, I would advise them to be showing a male lion and female leopard boarding the Ark rather than two lions as seen in all their advertising. This would seem weird to most of their target audience but they claim to be representing the best creation science has to offer on this ark.
Genetic bottlenecks are a serious challenge to all species when they occur. The negative effects of bottlenecking are well documented and profoundly effect the fate of species.* YECs are faced with a serious problem that challenges one of the most fundamental concepts that Ham’s post-flood evolutionary ideas depends upon: the presence of fantastic amounts of genetic variation in the progenitor to all current species. No amount of crossing over or hybridization can create new genetic variation/combinations where no variation already exists. The only thing a population that has bottlenecked can do is wait for mutations to add new variation to a population allowing the processes of natural selection and genetic drift to once again begin to act. Unfortunately for the YEC, mutations are not that common nor do most creationists want to invoke mutations as a source of genetic variation that natural selection can use to adapt a species to its environment because that sounds a lot like adding new information to a species and that would really sound like they are embracing evolution.
Below is a figure from another article I wrote on this topic: Are ruminants derived from a common ancestor?
* It isn’t always the case that species that are reduced to small numbers are sickly or not otherwise adapted to their environment. The remaining individuals may have few deleterious alleles and may, in fact, have lost some bad alleles that were in the larger population. But the bigger problem is that with reduced variation there is little for future populations to work with if the environment changes. In this way the long term viability of a species is in doubt. Some may do fine as they are for long periods of time. Cheetahs and walruses seem to be doing just fine but more species will go extinct under such conditions than will survive in the long run.