INTRODUCTION

This dissertation had its genesis many years ago when I was teaching high school and I started to muse on the probability of other intelligent forms of life in the universe. I also started to muse on the possible physical appearance of such forms and came to the rather astonishing conclusion that if there were intelligent life forms “out there” they would look very similar to us. I will attempt to prove the veracity of this strange claim by looking at the various factors that have affected the evolution of intelligent life on earth.

PHYSICAL FACTORS

When we consider the physical factors that have allowed intelligent life to develop on this planet I can think of no better place to start than that presented in the book “Rare Earth”, Brownlee & Ward, Copernicus books, 2000. In this seminal work the authors present convincing arguments in support of the hypothesis that the events, which have led to the earth becoming a planet upon which life forms could evolve, are exceedingly rare. The authors conclude by conjecturing that while simple microbial life may be relatively abundant in the universe intelligent life forms may be very few and far between. Not wishing to rehash their cogent arguments I will simply say that I agree with the authors and I too believe that intelligent life such as we know it on Earth must be exceedingly rare in the universe.

BIOCHEMICAL BASIS FOR LIFE ON EARTH

When one considers the biochemical basis for life on Earth one is immediately struck by the fact that although there are countless life forms on this planet, every single one is based on either DNA or RNA. When one thinks about this, several possible conclusions can be drawn:

It is not possible to build life using any other molecules except DNA or RNA
Other forms of life did originally exist on this planet but they lost out in the race for survival to DNA or RNA
There maybe other ways to form life but they just did not happen on Earth

Let us consider each of these statements in turn.

DNA and RNA are essential for the development of life

DNA and RNA are unique in the sense that they can encode vast amounts of information in a form, which can be easily translated and modified. It is true that certain proteins can do in part what DNA and RNA do but no molecules known to man can meet the condition of translation and modification quite so well as DNA and RNA.

Other forms of life did originally exist on this planet but lost out in the race for survival

If other forms of life inhabited this planet 3 scenarios can be examined:

These other forms evolved first
These other forms evolved contemporaneously with present life
These other forms evolved after DNA and RNA had become established

We can dismiss all of these scenarios by the same methodology. If the first forms had a head start they should have been able, as it were, to “protect their turf” since it is always harder to displace a well-adapted incumbent. However we find no evidence in the fossil record of any such displacement-taking place nor do we find any evidence of this earlier form of life to day.

If this other form of life was contemporaneous to present day life why do we not see evidence of these life forms today and finally for the 3^rd scenario it is even harder to credit this as being even viable since these forms would have had an uphill battle to start with, in trying to replace the incumbent species. All these arguments taken together seem to weigh heavily against any other form of life ever having become established on earth. So once again it seems that DNA and RNA life seem to be the only forms that work. I should make mention at this junction of the transpermia hypothesis i.e. that the earth was seeded by life forms from other planets. If this hypothesis is true it further strengthens the argument that DNA and RNA are the only molecules capable of forming the blueprint of life. If there were other forms then surely during the 4.5 billion years of earth’s evolution countless different life forms would have rained down on this planet. Since we find no evidence of these forms they therefore either do not exist or at least have not been able to gain a foothold on earth. Either way it would seem to show that DNA and RNA are the superior molecules needed to form the blueprint for life.

There are other ways to form life but they just did not happen on Earth

If we can dismiss other ways to form life on a planet like Earth from the previous arguments, it could be asked is it possible that there are other forms of life on planets, which differ radically from Earth? I.e. planets having liquid methane or nitrogen instead of liquid water seas. I think we can dismiss these possibilities because of the unique properties of water. Water is an ideal substance for life forms in that it is practically a universal solvent; it has a relatively high specific heat, latent heat of fusion and latent heat of vaporization. As a solid it floats on its liquid state and it is ubiquitous in both the solar system and the galaxy. I maintain therefore that other forms of life will also be based on water and more than likely DNA and RNA based. If I am right then we can say we have established the blueprint of life since we can study it here on earth and other planetary life forms must have evolved in much the same way that life evolved here. This means that we now have the means to ask, based on the DNA/RNA blueprint, “Are there many paths to the development of high intelligence or is there in fact only one way to do it”? In order to analyze this problem further let us identify the minimum factors needed to establish high intelligence here on earth.

FACTORS ABSOLUTELY NECESSARY FOR HIGH INTELLIGENCE TO DEVELOP ON EARTH LIKE PLANETS

Let us now consider the minimal factors necessary for intelligence to develop on an earth like planet considering first the medium the creature finds itself in.

Liquid (Most likely water) – I do not think that high intelligence can evolve in water for a number of reasons. The first and probably most obvious reason is that the body needs to be streamlined in order to glide easily through water. It is true that sessile creatures may not be streamlined but I think for the creature to be intelligent it must be fairly active and therefore not sessile. Since limbs need also to be streamlined arms and legs tend to become flippers even in animals, which previously had dextrous limbs, e.g. the forelimbs of whales have become flippers while the hind limbs have completely atrophied.

Another reason is that there is a comparative paucity of oxygen in water thus militating against a highly active life style, unless of course the creature is an air-breathing mammal returning to water.

A third reason relates to the comparative lack of care needed to protect the young in water thus militating against a long childhood where bonding and education can occur.

On earth the most intelligent of the marine creatures appear to be dolphins but it should be pointed out that they are warm-blooded, air-breathing mammals and are thus very active but even they cannot manipulate objects due to the need for streamlining.

Gas (Possibly air like) – In a gaseous medium everything has to be sacrificed so weight can be reduced. This means that even brains must be relatively small. A gaseous medium also militates against viviparity in that it would be difficult for a pregnant creature to fly. I think this would again argue against high intelligence in a medium like air.

Land – On land the competition for survival is, of course, intense, so it may legitimately be asked what would be the key factors affecting a creature’s ability to survive on any terrestrial type planet. Let us therefore list the main ones:

Fast running
Ability to suddenly take flight or swim
Ability to defend oneself vigorously e.g. having claws, horns, sharp teeth, being highly venomous, able to crush prey etc.
Ability to hide by burrowing
Having a large size
Able to camouflage oneself
Ability to hibernate
Having a spiny exterior
Extremely foul tasting
Emitting a noxious smell
Ability to detect other creatures before being detected
Warm blooded
Highly intelligent

The reader will notice I have left high intelligence for last. There is a good reason for this. Using earth as our model it is obvious that high intelligence is not necessarily the best strategy to pursue else, we should suppose, the earth would be teeming with highly intelligent creatures. It seems instead that for intelligence to be selected there must be obvious deficiencies in the other characteristics mentioned. We might therefore ask why, in terms of all creatures, should humans have attained high intelligence? I think the answer lies in terms of our obvious deficiencies in many of the other categories. In other words it is precisely because we are so deficient in these other abilities that there was such a strong selective pressure on intelligence. Why then might we ask did humans become so deficient that high intelligence was the only strategy left for development? It is through analyzing this question that we may finally be able to answer the original question, would intelligent organisms on other planets have to end up looking like us? Let us therefore consider each of the other characteristics in turn to try to understand why humans were unable to exploit these other strategies relating to survival.

Fast Running

If humans could run fast I very much doubt that there would have been much selective pressure for intelligence. But of course humans are descended from arboreal creatures where fast running was not a competitive advantage so this selective advantage was not open to them.

Ability to suddenly take flight or swim

Once again neither of these adaptations was open to humans in that large arboreal creatures certainly cannot fly and since the best method of escape was always to another branch, not a pond or river, there was no selection for an ability to swim or fly.

Ability to defend oneself using claws, teeth, horns etc.

Arboreal creatures really are not designed to stand and fight. Agility in tree precludes a very large mass and horns and antlers would simply get in the way. So once again these options were really not open for exploitation by humans.

Ability to hide by burrowing

Clearly an arboreal life precludes burrowing so we need say no more about that.

Having a large size

As has been previously stated having a large size is not compatible with the arboreal life.

Ability to camouflage oneself

This might have been an adaptive advantage but probably was not selected since it is very easy to hide in a tree without camouflage.

Ability to hibernate

Human evolved in tropical climates where there is no need for hibernation when food supplies are low, thus this characteristic was never selected.

Having a spiny exterior

A spiny exterior would be a considerable disadvantage to arboreal creatures so there must have been a positive environmental pressure against such a characteristic developing.

Foul tasting

If an organism is adept at escaping from its enemies then the need to be foul tasting is not an adaptive advantage and therefore was not selected.

Emitting a noxious smell

Arboreal creatures do not need this characteristic since they can easily escape by jumping from one branch to another so once again we have no selective pressure in favour of this property.

Ability to detect others before being detected

Here the property of sight was a huge adaptive advantage and in particular the binocular vision needed to judge depth as a creature leaps from branch to branch. Acute hearing and smell were not needed to the same degree hence our abilities to smell and hear do not compare favourably with many animals.

Warm blooded

Being warm blooded was a definite adaptive advantage in that it allowed arboreal mammals to be active at all hours of the day and night. Thus they could escape their predators and catch prey more easily either day or night.

High intelligence

We now arrive at the final factor, high intelligence. Why, of all creatures, was high intelligence the characteristic most consistently selected for in humans? I submit it was selected because it was the only weapon left in the arsenal. The reason high intelligence has not been selected more often is because it brings with it lots of baggage.

Consider the following factors, which have to be addressed if high intelligence is to have any value in terms of survivability.

The young must be born in a relatively vulnerable state in order that their brains can grow to full maturity outside the womb.
Notwithstanding the above stipulation, the mother’s ability to expel the infant at birth is very much constrained in terms of the opening in the pelvis through which the comparatively large infant’s head must pass at the time of delivery.
Because of the difficulty in expelling the infant at birth the child is born facing the wrong way and therefore the mother requires assistance in the delivery of the child
Due to the modifications of the pelvic structure to allow birth, the female’s thigh bones are set out at angle, which compromises her ability to run and walk in the most efficient manner.
The cranium of the neonatal human infant has two fontanels to allow for the expansion of the brain. This makes the newborn child very vulnerable to head trauma.
The human infant is born in a particularly helpless and vulnerable state and requires constant care and supervision for many years. This places a great deal of stress on the mother both nutritionally in the provision of milk and observationally in the monitoring of the infant.
The mother’s arms are occupied with cradling her child thus making the mother very vulnerable to attack from predators.

When one considers these 7 points as a package one can easily wonder why, with all these obvious disadvantages, was high intelligence ever selected in the first place? Surely the only conclusion that can be drawn is that the advantages of high intelligence are so overwhelming that despite all the disadvantages it was still a viable evolutionary strategy. Let us now speculate as to how this came about.

How high intelligence was selected

If we roll the clock back 6 million years we arrive at a time when our forbears were practicing a survival strategy involving ground foraging and escape to trees once danger was observed. The problem with this strategy is that one can’t be good at both. If one’s feet are adapted to grasping tree limbs then they are not much good for walking; if on the other hand they are adapted to walking they are not much use for climbing trees. What to do?

It seems fairly early on; perhaps as far back as 6 million years ago, the hominid foot became adapted to walking and thus lost its ability to grasp tree limbs. Why? The answer must surely have been that there was a compelling need to find food on the forest floor due to the relatively large size of the early hominids compared to most other primates and their high metabolic rate. Unfortunately the forest floor is a very dangerous place to be for large aggressive predators hunt there and hominids must have been seen as very attractive prey. How could these early hominids have defended themselves? Let us consider some of their attributes, which would have aided their survival.

Binocular vision – this allowed hominids to judge distance very accurately i.e. how far away is the predator?
Colour vision – this allowed the hominid to better identify camouflaged creatures.
Relatively large size – this enhanced defensive ability
Social cohesion – this allowed hominids to unite against a common enemy
Relatively high intelligence – this afforded greater adaptability

All of the above attributes developed from the hominids arboreal ancestry.

However against these relatively few positive attributes there were many negative ones.

Inability to run fast enough to escape potential predators
Great vulnerability of the human infant
Relatively low strength to weight ratio
Inability to escape a predator by swimming or flying
Lack of agility in climbing trees
Lack of sharp teeth, claws, or horns.

Why then did these early hominids survive at all with so many strikes against them?

Why the early hominids survived

Let us now cast our minds back six million years ago and imagine we are hunter-gatherers struggling to survive in the open woodland of the east African savannah, let us also conceptualize about the difficulties we face. Firstly the plains would be teeming with all kinds of life ranging from extremely large herbivores to very dangerous large carnivores. To a hungry lion a lone hominid would seem very easy prey. Surely therefore one of the strategies for survival would be to forage in groups with the obvious advantage that there would be several pairs of eyes to raise an alarm. Another strategy would be to make use of arms and hands to carry sticks and stones. How do these two factors tie in to the evolution of high intelligence?

Considering the first factor one can easily see that improved communication would certainly improve survivability. More sophisticated communication means more sophisticated neuronal structures so there was a definite positive feedback loop towards more complex brains in the area of communication.

With regards to the second factor those hominids, which learned first how to sharpen sticks to make them more useful weapons, would certainly have an advantage over others who had not learned this skill. I therefore maintain that there was a strong feedback loop on both counts towards higher intelligence. However, here we run into a problem, if there were strong feedback loops for the early hominids why would there not also be similarly strong feedback loops for other organisms fighting for survival on the African plains? The answer to this question goes back to dexterity. Only those organisms having the ability to manipulate tools would experience the strongest feedback loops for neuronal complexity. Since primates, more than any other creatures, can manipulate artefacts they would experience the strongest feedback loops towards greater and greater manual dexterity.

Why though have humans, more than any other creatures on this planet, achieved that most complex mode of communication, namely language? It is certainly true that other organisms can have quite complex vocal signals, consider for example the great whales, but still, only humans have developed language in its most complex form. Why? I don’t have a ready answer but I would like to conjecture that the strong feedback loop towards greater and greater manual dexterity was somehow coupled to language. This field of research needs more thorough investigation.

We may conclude this section in this way. Although more research needs to be done in the field of language acquisition, clearly only humans experienced the strongest feedback loops towards greater and greater mental complexity.

Can only primates experience the strongest mental complexity feedback loops?

If, as I have tried to argue, only animals possessing high manual dexterity experience the strongest mental complexity feed back loops it may legitimately be asked why did dinosaurs not experience the same loops 100 million years ago? Many dinosaurs walked on 2 legs thus their upper limbs were free. However they did not have opposable thumbs, like the later primates, nor did they have binocular vision. These two factors alone would strongly militate against an enhanced mental complexity feedback loop. Since they were probably not warm-blooded nor did they care for their young it would further argue against the development of higher intelligence. Obviously the dinosaurs never did achieve high mental complexities else we should have plenty of evidence of that today in the form of ancient cities well over 100 million years old. Perhaps there is also a synergy between a very long pre-pubertal development and mental complexity.

Would life on other planets follow the same trajectory as life on earth?

If the tenets for the rare earth hypothesis are correct then there are relatively few planets like earth in any given galaxy, although in terms of the whole universe there may be many. Because there are relatively few earth like planets scattered over vast distances I think the transpermia hypothesis is extremely unlikely, therefore, each earth like planet would have to develop life in its own way. Since, as I have already shown, there appears to be only one way to form life on earth I argue the same is probably true for other earth like planets. Since during the course of the evolution of life on earth the trajectory moved from simple to complex and from water to land I conjecture that the same would be true for other earth like planets. Since during the 3.5 billion years that life has existed on earth only one highly intelligent species has developed I am forced to conclude that it would take that period of time on any other planet. Since only primates developed the manual dexterity needed to feed the demands of a growing intelligence I must conclude that the arboreal way of life is essential for this development. Since 25% of all the oxygen available in the blood is consumed by the human brain I must conclude that for a creature to develop intelligence it must have an efficient way of delivering oxygen to all parts of the body i.e. a 4 chambered heart. Since the demand for such an efficient heart was necessitated by being warm blooded I am forced to conclude that a creature must be warm blooded for high intelligence to be attained. Since one of the spurs to high intelligence in humans was the need to cooperate in groups I am forced to conclude that alien organisms must also have had to develop appropriate communication skills and probably, like humans, have a delayed development.

Now the curious thing is that all primates on earth have a very similar body plan which would indicate to me that this was the only plan viable in the context of earth, If other planets are forced to be very similar to earth for reasons already mentioned then surely the same forces “guiding” their evolution of life must be operant there. In other words they maybe only one way to produce a creature of high intelligence and that is the way of

Earth. If all the above is true, and I cannot see the flaws in my argument, then any creature with high intelligence would end up looking like us.

Now just to make myself abundantly clear I don’t mean to say that their genotype will be exactly the same as ours but what I do mean is that their phenotype will end up being very similar to ours. Now there may be some marked differences in say mating behaviour or in dietary requirements but I still think we shall be surprised as to how similar they are to us in physical appearance.

Could life evolve in an alternate universe?

Most scientists today believe that our universe started as a tiny patch of space time 13.7 billion years ago. This patch, perhaps as small as a billionth of the size of a proton went through a rapid expansion producing the 4 fundamental forces and all the matter we see today. It is possible that alternate universes were formed where these fundamental forces were different. However any tinkering with three of these fundamental forces namely the strong, electromagnetic and gravitational force would end up producing a universe incapable of supporting life. If the weak force did not exist then neutrons could not be turned into protons and vice versa. In such a universe there would be few if any elements beyond iron in their periodic tables and even if life existed it would be compromised to some degree. “Looking for Life in the Multiverse”, Jenkins and Perez, Scientific American, January 2010 pp.42-49.

CONCLUSION

I have attempted to show in this short paper that if intelligent aliens exist they would look remarkably like us. I have also attempted to show that probably only in a universe like ours may life exist at all. Considering the extreme improbabilities of certain events happening which allowed life to form on earth, intelligent life may be exceedingly rare in our universe. This would answer the Fermi paradox, which states:

The apparent size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist.
However, this hypothesis seems inconsistent with the lack of observational evidence to support it. (Wikipedia)

When one considers in total all the improbable events, which had to happen to create intelligent life on this planet, it is a wonder we humans exist at all. It may be we are alone in this mighty universe and indeed in all universes which raises the obvious theological question that if a God exists did he have to create a mighty universe in order to create man? If so, why would he do that?

The Evolution of Intelligence in our Universe

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Saturday, November 13, 2010

FACTORS AFFECTING INTELLIGENCE