The Mathematics of Genetic Success

Of all the factors that account for the existence of humankind the most significant is that of luck. We have been fortunate to have chosen the genetic pathways to get us where we are today. They have ensured our survival and our undeniable success as a species.

There is a saying, “you make your own luck.” Whether that is true in genetic terms I’m not sure but we have certainly taken advantage of those opportunities that have become available to us.

Genetic progress is primarily achieved through mutations that convey adaptations to give an environmental advantage and which therefore hold some appeal making them attractive and subsequently encouraging their proliferation.

Genetic success is geared to reproduction. That is the moment when any improvements can be made to a species. That is when change happens. So, in order to be successful, a species must, first and foremost, reproduce effectively.

Logically, it follows that the largest population with the optimum breeding programme will have the best chance to be genetically successful. This is because, through large scale and astute reproduction, they will give themselves the most opportunities to achieve advantageous adaptations.

The more times you go fishing the more likely you are to catch something; the better your fishing knowledge and technique the more likely you are to catch something.

Reproduction leads to genetic progress but, as a species, in order to ensure survival, that rate of genetic advancement needs to equal or be greater than the environmental forces exerted upon it.

Mathematically this can be represented as follows:

Size of Population 

X

Fertile Efficacy

X

Level of Mutative Action

=

Rate of Genetic Advancement

Rate of Environmental Change

To understand this mathematical formula in more detail we need to delve into its component elements:

Size of Population: This is the total size of the species population. It is the bank from which reproduction has to operate from.

Fertile Efficacy: (Reproductive Rate and Reproductive Strength and Diversity) relates to the effectiveness of the population in achieving reproduction itself and, also, the extent to which that reproduction is progressive. It is essentially comprised of two factors. Firstly, the Reproductive Rate which primarily is the level of reproduction in a species; how many off-spring does an individual have? It is a measure of the quantity of reproduction that is taking place. It will vary between species and even possibly within a species.

The Reproductive Rate is determined by the following:

Firstly, the resources available. The availability of the required resources is the key as to whether or not an off-spring can be successfully raised. If the means of survival such as food and shelter are not available then the Reproductive Rate of a species will decline. Similarly, when resources are abundant Reproductive Rates will increase. This is evidenced by the fact that some animals can biologically increase their reproductive capacity when they have the chance to.

Generally, the biology of a species will determine its Reproductive Rate – the length of fertility and the number of off-spring in a single reproductive cycle being fixed. However, there is some flexibility in this. Over a long period, given favourable environmental conditions (that is, plentiful resources), a species may actually adapt its biology to take advantage of added reproductive opportunities.

This may, in certain circumstances, even be seen as a short term phenomenon. It may, in part, determine the number of eggs a bird will lay. It may be one of the reasons why animals have runts in litters – they’re gambling that it might be a bumper year for resources which would give the runt a chance of survival.

The second factor in determining Reproductive Rate is the investment required to raise an off-spring. The great parenting unknown is that, for the most part, parents are unaware of the genetic traits and talents of their off-spring. Their off-spring may or may not prove to be a great contributor to that species’ genetic advancement. Given that such uncertainty exists parents tend to approach the matter by working with what they already have.

Raising an off-spring requires a substantial investment of time. It also takes the parent out of the reproductive process. Their gamble is that they are concentrating their resources on the investment they have already made, knowing that any further reproductive endeavours are not guaranteed to either be successful or to produce something better than that which already exists.

Underlying the reproductive challenge there always endures the classic quality versus quantity dilemma – go for more or go for better.

The second factor in Fertile Efficacy is Reproductive Strength and Diversity. This is more of a quality and performance measure.

Strength arises from the nature of the genetic materials being used. Are the elite of the species being the most reproductive? The more that a population reproduces from the best of its crop then the more likely it will go on to achieve higher levels of genetic excellence.

In terms of strength; the most desirable and therefore the most productive may be the biggest, the fastest, the most flamboyant, the best hunter, the best nest builder.

Diversity relates to the variety of the mix. There may be genetic combinations that generate advantageous mutations. Is reproduction tapping into the full range of genetic possibilities available to it? And, of course, the more a species can avoid in-breeding the better its prospects.

In terms of diversity, at some point off-spring have to leave their parents. Where they go will have a significant bearing on the diversity of their reproductive fruits. An example of a species pursuing diversity would be when a mother elephant expels the young male from the herd so he has to wander the plains until he finds another elephant herd that he can take a mate in.

Strength and Diversity are all about maximising potential.

Level of Mutative Action: Given that species development relies on mutations to occur which, when deemed beneficial, can spread throughout the population, the notion of a level of Mutative Action relates to the likelihood of a mutation occurring in any given reproduction. What propensity is there to mutate? Does that vary within a species? Are there different degrees – some being more significant than others – to which mutation takes place? Are there different levels of viability with mutations? Do these mutative variables differ between species or are they a constant and can be applied equally to all species? This is a genetic unknown and difficult to quantify.

Rate of Genetic Advancement: This figure relates to the progress a species is making in terms of its development and can be compared with the Rate of Environmental Change. It could also be an effective tool for comparing species or for comparisons between species populations at different times.

It should be noted that the nature of the evolutionary system means that genetic retreat or decline is not a realisable outcome. Mutations that don’t add to the worth of a species just disappear. Hence the use of the term advancement rather than a reference to change.

And of course genetic advancement is not something we can visually observe in the present. We don’t know whether particular actions will or will not be genetically enhancing. As a reproductive individual we can only do what we feel is right. Quite often this is what we are genetically programmed to do. It explains why male lions will often kill the cubs of rivals.

Rate of Environmental Change: Our environment is subject to constant change. It is never static. Change can occur in a couple of ways:

Firstly, due to the effect of nature’s forces – geological change (volcanoes, rivers, oceans, earthquakes) and meteorological change (weather patterns).

Secondly, changes in relation to other biological species that a particular species may have some interaction with. The fact that all other living things are subject to genetic mutation means that change is endemic to the system. Any change for one living thing will have implications for others. Species A has acquired a new skill. Species A’s new ability impacts on species B. Species B must learn its own new skill that either protects itself from species A’s new skill or negates any effect of that skill.

The process of genetic adaptation can be compared with that of cooking a new recipe. The more times you cook it and the more you tweak the ingredients – both what you include and the quantities you add – the more chances you have to improve the recipe.

The success of a species is therefore measured by whether or not the rate of genetic advancement matches or exceeds the rate of environmental change. In practical terms this can be observed by looking at changes to the population size, by death rates, by stress levels within a species, by the proportion of time that the species has to devote to survival activities such as finding food, shelter and procreation.

In terms of examples, contrast pandas with their low population size, low reproductive rate and low reproductive strength and diversity with mice which score high on all three counts. It explains why mice have the better rate of genetic advancement and are successful in their environment.

Considering the human species, we have been very successful. We have stayed ahead of the game. We have a substantive base to work from given our population size. And although our reproductive rate tends to be on the low side this is compensated for by the strength and diversity of our reproduction.

In the past the focus tended to be upon maximising genetic strength – the Alpha male would be the most successful reproducer. He would have his pick of the female population. More recently, we have shifted towards reproductive diversification as the source of our genetic improvement. This is apparent in a number of ways: changes in social mobility, geographical spread, cultural mixing, the breaking down of racial exclusivity. We are therefore reproducing from a wider spectrum. We are adding to the genetic mixing pot.

A conclusion to be taken from this mathematical understanding is that if our (perhaps rather prejudicial) viewpoint is that human beings are the most advanced creatures on the planet we should really think again. This is not so. To think this is to be measuring Genetic Advancement incorrectly. Advancement is not an assessment of our way of life or our richness of being. Correctly measured, advancement is, instead, a measure of our genetic position relative to that of our environment.

In reality, from a genetic perspective, it may well be that mice or some unapplauded insect is superior to us.

During normal circumstances, so long as a species matches or does better than any environmental change it will continue to survive and prosper. However, there may be times when an environmental spike occurs. Disease, virus, a new predator, weather change, meteor strike or some other catastrophe – these events may dramatically change the environment. It is the ability of a species to adapt and triumph over that new environment which is the real challenge and test for its Rate of Genetic Advancement.

Dinosaurs are a classic example. They failed to adapt sufficiently and in time in relation to their new environment. They were slow to reproduce and the numbers weren’t there to give them a sufficient base to ensure that the reproduction that did take place produced enough effective mutations to enable them to adapt to the new environment. Hence their extinction.

During that time, those species that did successfully adapt – birds, some amphibians, insects, did so because they were either mass producers (had lots of off-spring and therefore, by sheer weight of numbers, had the chance to acquire an effective adaptation) or were able to tap into some genetic strength and diversity within their species.

The implication is that if threatened by some detrimental environmental force then a species may need to change its reproductive behaviour in order to ensure its genetic survival.

Failure to do so could put it on a downward spiral towards extinction.

Currently, humanity continues to be successful because we have developed through, amongst other things, technology, communication and social relationships the requirements to tap into the full genetic resources available to us. It means that we have continued to outstrip changes to our environment. Of course, there are no guarantees. Things could change and, if they did, we would have to adapt accordingly.

We should never presume any superiority over other forms of life. Nor that our position is sacrosanct. We have just been lucky. We have made the right genetic advances. It could have turned out very differently. It may still do so.

© Copyright Steve Oxley 2020