The Meaning of Human Existence (16 page)

Granted there are positive consequences to blind faith. It binds groups more strongly, and provides comfort to their members. It promotes charity and law-abiding behavior. Possibly the dogma load is made more tolerable by these services. Still, the ultimate force driving blind faith is not a divine afflatus. It is instead certification
of membership in a group. The welfare of the group and defense of its territory is biological, not supernatural in origin. Except in theologically repressive societies, it has proved easy for individuals to shift religion, marry across religions, and even drop them entirely without loss of morality or, of equal importance, the capacity for wonder.

There are other archaic misconceptions outside religion that have weakened culture, albeit with a more logical and honorable rationale. The most important is the belief that the two great branches of learning—science and the humanities—are intellectually independent of each other. And more, the farther apart they are kept, the better.

I’ve argued here that while scientific knowledge and technology continue to grow exponentially, doubling every one to two decades according to discipline, the rate of increase will inevitably slow. Original discoveries, having generated vast knowledge, will ease off and begin to decline in number. Within decades, knowledge within the technoscientific culture will of course be enormous compared to that of the present, but also the same everywhere in the world. What will continue to evolve and diversify indefinitely are the humanities. If our species can be said to have a soul, it lives in the humanities.

Yet this great branch of learning, including the creative
arts and their scholarly criticism, is still hampered by the severe and widely unappreciated limitations of the sensory world in which the human mind exists. We are primarily audiovisual and unaware of the world of taste and smell in which most of the millions of other species exist. We are entirely oblivious to the electrical and magnetic fields used by a few animals for orientation and communication. Even in our own world of sight and sound we are relatively close to blind and deaf, able to perceive directly no more than minute segments of the electromagnetic spectrum, nor the full range of compression frequencies that surge past us through earth, air, and water.

And that is just the start. Although the details of the creative arts are potentially infinite, the archetypes and instinct they are designed to exemplify are in reality very few. The ensemble of emotions that produce them, even the most powerful, are sparse—fewer in number than, say, the instruments of a full orchestra. Creative artists and humanities scholars by and large have little grasp of the otherwise immense continuum of space-time on Earth, in both its living and nonliving parts, and still less in the Solar System and the Universe beyond. They have the correct perception of
Homo sapiens
as a very distinctive species, but spend little time wondering what that means or why it is so.

Science and the humanities, it is true, are fundamentally different from each other in what they say and do. But they are complementary to each other in origin, and they arise from the same creative processes in the human brain. If the heuristic and analytic power of science can be joined with the introspective creativity of the humanities, human existence will rise to an infinitely more productive and interesting meaning.

Appendix

The Limitations of Inclusive Fitness

Because of the importance of genetic theory used to explain the biological origins of altruism and advanced social organization, and the much-publicized recent controversy surrounding it, I have included here a recent analysis of the theory of inclusive fitness, and the reason it should be replaced by data-based population genetics. The material presented is of a previously published research report, with the mathematical analyses and references deleted. The article was subject to intense expert review prior to publication.

Reference: “Limitations of Inclusive Fitness,” by Benjamin Allen, Martin A. Nowak, and Edward O. Wilson,
Proceedings of the National Academy of Sciences USA
, volume 110, number 50, pages 20135–20139 (2013).

Significance

Inclusive fitness theory is the idea that the evolutionary success of a trait can be calculated as a sum of fitness effects multiplied by relatedness coefficients. Despite recent mathematical analyses demonstrating the limitations of this approach, its adherents claim that it is as general as the theory of natural selection itself. This claim is based on using linear regression to split an individual’s fitness into components due to self and others. We show that this regression method is useless for the prediction or interpretation of evolutionary processes. In particular, it fails to distinguish between correlation and causation, leading to misinterpretations of simple scenarios. The weaknesses of the regression method underscore the limitations of inclusive fitness theory in general.

Until recently, inclusive fitness has been widely accepted as a general method to explain the evolution of social behavior. Affirming and expanding earlier criticism, we demonstrate that inclusive fitness is instead a limited concept, which exists only for a small subset of evolutionary processes. Inclusive fitness assumes that personal fitness is the sum of additive components caused by individual actions. This assumption does not hold for the majority of evolutionary processes or scenarios. To sidestep this limitation, inclusive fitness theorists have proposed a method using linear regression. On the basis of this method, it is claimed that inclusive fitness theory (i) predicts the direction of allele frequency changes, (ii) reveals the
reasons for these changes, (iii) is as general as natural selection, and (iv) provides a universal design principle for evolution. In this paper we evaluate these claims, and show that all of them are unfounded. If the objective is to analyze whether mutations that modify social behavior are favored or opposed by natural selection, then no aspect of inclusive fitness theory is needed.

Inclusive fitness theory is an approach to accounting for fitness effects in social evolution. It was introduced in 1964 by W. D. Hamilton, who showed that, under certain circumstances, evolution selects for organisms with the highest inclusive fitness. This result has been interpreted as a design principle: evolved organisms act as if to maximize their inclusive fitness.

Hamilton defined inclusive fitness as follows:

Inclusive fitness may be imagined as the personal fitness which an individual actually expresses in its production of adult offspring as it becomes after it has been first stripped and then augmented in a certain way. It is stripped of all components which can be considered as due to the individual’s social environment, leaving the fitness which he would express if not exposed to any of the harms or benefits of that environment. This quantity is then augmented by certain fractions of the quantities of harm and benefit which the individual himself causes to the fitnesses of his neighbours. The fractions in question are simply the coefficients of
relationship appropriate to the neighbours whom he affects: unity for clonal individuals, one-half for sibs, one-quarter for half-sibs, one-eighth for cousins . . . and finally zero for all neighbours whose relationship can be considered negligibly small.

Although modern formulations of inclusive fitness theory use different relatedness coefficients, all other aspects of Hamilton’s definition remain intact.

The crucial point here is that it is assumed that personal fitness can be subdivided into additive components caused by individual actions. The personal fitness of a focal individual is stripped of all components that are due to the “social environment.” This means we have to subtract from the personal fitness of an individual every effect due to other individuals. Subsequently we have to calculate how the focal individual affects the personal fitnesses of all other individuals in the population. In both cases we must assume that personal fitness can be expressed as a sum of components caused by individual actions. Inclusive fitness is the effect of the action on the actor plus the effects of the action on others multiplied in each case by the relatedness between the actor and the others.

It is immediately obvious that the additivity assumption, which is essential for the concept of inclusive fitness, need not hold in general. For example, the personal fitness of an individual can be a nonlinear function of the actions of others. Or the survival of an individual could require the simultaneous
action of several others; for example, the reproductive success of the queen ant might require the coordinated action of groups of specialized workers. Experiments have found that the fitness effects of cooperative behaviors in microbes are not additive. It is clear that in general fitness effects cannot be assumed to be additive.

Two Approaches to Inclusive Fitness

Within the literature on inclusive fitness, there are two approaches for dealing with the limitation of additivity. The first approach is to restrict attention to simplified models in which additivity holds. For example, William D. Hamilton’s original formulation of inclusive fitness theory includes additivity as an assumption. Additivity also follows from assuming that mutations have only small effects on phenotypes, and that fitness varies smoothly with phenotypes.

M. A. Nowak, C. E. Tarnita, and E. O. Wilson investigated the mathematical foundations of this first approach. They demonstrated that this approach also requires a number of restrictive assumptions beyond additivity of fitness effects, and is therefore applicable only to a limited subset of evolutionary processes. In response, more than one hundred authors signed the statement that “inclusive fitness is as general as the genetical theory of natural selection itself.” How are we to understand this apparent contradiction?

The answer is that the above statement rests on a second,
alternative approach, which deals with the additivity problem in retrospect. In this approach, the outcome of natural selection must already be known or specified at the outset, and the objective is to find additive costs and benefits that would have yielded this outcome—regardless of whether they correspond to actual biological interactions. The cost (
C
) and benefit (
B
) are determined using the linear regression. The change in gene frequency is then rewritten in the form
BR
-
C
, with
R
quantifying relatedness. This regression method was introduced by Hamilton in a follow-up to his original work on inclusive fitness theory, and has been subsequently refined into a recipe for rewriting frequency changes in the form of Hamilton’s rule.

The regression method underpins many claims of the power and generality of inclusive fitness theory. For example, it is often claimed that the regression method allows inclusive fitness to eschew the requirement of additivity. It is also claimed that the regression method generates a prediction of the direction of natural selection, and leads to a quantitative understanding of any frequency change as a consequence of social interactions between related partners.

Here we evaluate these claims by asking what, if anything, the regression method reveals about a given evolutionary change. We show that claims of the method’s predictive and explanatory power are false, and the claim of its generality is not a meaningful one that could be evaluated. These findings call into question the idea that inclusive fitness provides
a universal design principle for evolution—indeed, no such design principle exists.

Regression Method Does Not Yield Predictions

We now evaluate the various claims made regarding the regression method, starting with the claim that it predicts the direction of selection. This claim cannot be true, because the allele frequency change over the considered time interval is specified at the outset. The “prediction” merely recapitulates what is already known, such that the sign of
BR
-
C
agrees with the predetermined outcome.

The regression method also does not predict what will happen over different time intervals or under different conditions. With any change in the considered scenario or time interval, the starting data must be respecified and the method reapplied, yielding new and independent results.

This lack of predictive power is unsurprising. It is logically impossible to predict the outcome of a process without making prior assumptions about its behavior. In the absence of any modeling assumptions, all that can be done is to rewrite the given data in a different form.

Experimentalists have noticed this absence of predictive capacity. One recent study applied the regression method to the cooperative production of an agent needed for antibiotic resistance in
Escherichia coli
. The authors conclude that “even if one has measured the values of
B
,
C
and
R
for a particular system
of producers and nonproducers, one cannot predict what will result from changing either the structure of population or the biochemistry of the individuals.”

Regression Method Does Not Yield Causal Explanations

We now evaluate the explanatory power of the regression method. The current literature appears to disagree on this point. Some works claim the method yields causal explanations for frequency change, whereas others make the more limited claim that it provides a useful conceptual aid. Moreover, the quantities that result from the regression method are commonly described in terms of social behaviors such as altruism and spite, imbuing these quantities with a “causal gloss” even if no direct claims of causality are made.