If you’re a Humanist, then accepting Darwin’s theory of evolution comes with the territory. It’s even written into the second and third versions of the Humanist Manifesto. Here’s what the second version has to say, published in 1973:

Using technology wisely, we can control our environment, conquer poverty, markedly reduce disease, extend our life-span, significantly modify our behavior, alter the course of human evolution and cultural development, unlock vast new powers, and provide humankind with unparalleled opportunity for achieving an abundant and meaningful life. Modern science discredits such historic concepts as the “ghost in the machine” and the “separable soul.” Rather, science affirms that the human species is an emergence from natural evolutionary forces. As far as we know, the total personality is a function of the biological organism transacting in a social and cultural context. There is no credible evidence that life survives the death of the body. We continue to exist in our progeny and in the way that our lives have influenced others in our culture.

And here’s what the third version has to say, published in 2003.

Humans are an integral part of nature, the result of unguided evolutionary change. Humanists recognize nature as self-existing. We accept our life as all and enough, distinguishing things as they are from things as we might wish or imagine them to be. We welcome the challenges of the future, and are drawn to and undaunted by the yet to be known.

These two manifestos are mere snapshots of the Humanist movement at different points in time, but the snapshots are revealing. The second manifesto portrays evolution as something that can be guided. We can alter its course to achieve a more abundant and meaningful life. The third manifesto goes out of its way to say that evolutionary change is unguided. Whatever else the third manifesto has to say about achieving a more abundant and meaningful life has become detached from its rendering of evolution.

Recent developments in evolutionary science challenge the idea that evolution is entirely unguided, making the second version of the Humanist Manifesto more accurate than the third version. This is not just a quibble, because it speaks to the role that evolutionary science needs to play if the goals of both manifestos—a more abundant and meaningful life for all—is to be achieved.

Enter the phrase “Extended Evolutionary Synthesis (EES)” into your favorite search engine and you can sample the recent developments for yourself (I suggest starting here: 1, 2, 3, 4, 5). Proponents of the EES make the relatively modest sounding claim that our knowledge of evolution has gone beyond a synthesis that emerged in the 1940’s and became known as The Modern Synthesis (MS). Our current knowledge is not a clean break from the past, therefore not a brand new synthesis, but sufficiently different to deserve a linguistic marker—hence The EES.

The concept of evolution as an entirely unguided process is one of the tenets of the MS that is being challenged by the EES. Early evolutionary thinkers such as Lamarck thought that the direction of evolution could be guided by the activities of an organism. For example, if a herbivore spends its life stretching its neck to eat tree leaves, its progeny will be born with longer necks. Darwin himself entertained this notion and it was August Weismann (1834-1914) who forcefully asserted that the reproductive cells are sequestered from and uninfluenced by the cells that make up the rest of the body. This claim was supported by the work of Gregor Mendel that initiated the science of genetics. By the 1940’s, the idea that genetic variation is random with respect to what the environment selects became a central tenet of the MS. The ideas associated with Lamarck were branded as wrong as wrong can be.

Three lines of evidence have led to a revival of Lamarkian thinking as part of the EES. First, organisms can change the frequency of mutations and in some cases the direction of mutations in response to environmental stress. Second, it is now firmly established that changes in gene expression (epigenetics) that take place during the lifetime of an organism can be transmitted to its offspring. These guided forms of evolution are compatible with the MS because they can be shown to have evolved by unguided evolution. For example, consider a random genetic mutation that increases the rate of other mutations in certain regions of the chromosomes in response to certain environmental stressors. This mutation can evolve, so that the patterns of mutation are no longer random. If guided evolution can evolve from unguided evolution, then the categorical rejection of Lamarckian thinking is unwarranted.

The third line of evidence is even more important. If behaviors learned during one generation can be socially transmitted to the next generation, then this would qualify as a guided form of evolution. Transgenerational social learning resulting in cultural traditions has been documented in many species, with our own species as the premier example.

Given that cultural evolution is a (partially) guided process, how could the third Humanist Manifesto insist that evolution is unguided? In part because the study of evolution became highly gene-centric during the 20th century, as if the only way that offspring can resemble their parents is by sharing genes. The study of culture was left to cultural anthropologists, who for the most part regarded human cultural change as something that happens outside the orbit of evolutionary theory (go here for more).

It wasn’t until the late 20th century that evolutionary scientists went back to basics and defined heredity as the transmission of information across generations, with genes as only one of several mechanisms of inheritance. In their influential book Evolution in Four Dimensions, Eva Jablonka and Marion Lamb identify four mechanisms: genetics, epigenetics, forms of social learning found in many species, and forms of symbolic thought that are distinctively human (go here for a TVOL interview with Jablonka). That book was published in 2005, two years after the publication of the third Humanist Manifesto. Since then, there has been an explosion of research on the human capacity for cultural change as both a product of genetic evolution and an evolutionary process in its own right (go here for a review of four recent books).

This research can and should be transformative for the Humanist movement. It is the essence of Humanism to take responsibility for improving the human condition, using science and reason as our guides. The first Manifesto managed to say this without using the word evolution at all. The second Manifesto described it as a guided form of evolution and the third Manifesto made evolution seem peripheral by describing it as an unguided process. What we have now, almost entirely since the last Manifesto was written, is a set of conceptual tools for “becoming wise managers of evolutionary processes 1” more than ever before.

As someone who is pursuing a Humanist agenda through the Evolution Institute, which I started with the Humanist Jerry Lieberman under the auspices of the Humanists of Florida Association, I am concerned that the rest of the Humanist movement has been slow to realize the potential of modern evolutionary science for achieving practical Humanist objectives. Instead, evolution is being used primarily as a weapon against religion, which misconstrues the very nature of religion that can be enlightened from an evolutionary perspective (go here for a video tutorial) 2,3. I don’t know when a fourth version of the Humanist Manifesto will be written, but when it is, I recommend that it include a section on evolution like this one:

Modern science has shown that the human capacity for change is both a product of genetic evolution and an evolutionary process in its own right. Also, what counts as adaptive in the evolutionary sense of the word often deviates from normative goals for achieving an abundant and meaningful life for all. This means that it is necessary to manage cultural evolutionary processes to achieve the normative goals of Humanism. Humanism has always used science and reason as its compass. Now it has a new set of navigational tools provided by evolutionary science for achieving its practical objectives.

We needn’t wait for a fourth Humanist manifesto to take this passage to heart and put it into action. Along with my co-founder Jerry Lieberman, I invite all Humanist individuals and organizations to join us in exploring how to understand and improve the human condition from an evolutionary perspective.



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