The End of Darwinism: How Humans Are Overriding Evolution

Virtual Presentation with Roger Ibbotson, Professor Emeritus of Finance at Yale School of Management

Examining all species from a Darwinian perspective enables us to understand how humans impact our planet’s environment. It starts with humans, who have overridden evolutionary adaptation by having almost all our children survive. Our population has exploded as we have gotten richer (contradicting Malthus). Instead of genetic evolution, we are adapting through technology and changing culture. We have industrialized agriculture, domesticating animals and plants through human selection so that they no longer resemble their ancestors. Wild species are still adapting through natural selection. Still, evolution is mostly a slow process, and herbicides, pesticides, hunting, habitat loss, pollution, climate change, etc, threaten many species. Understanding ecology from a “big picture” perspective might help steer us into more intelligent policy decisions.

Presentation Date: August 29th, 2023



Download a PDF of the working paper “The End of Darwinism: How Humans Are Overriding Evolution

The End of Darwinism: How Humans Are Overriding Evolution – Presented by Professor Roger Ibbotson

Roger Ibbotson

Professor in the Practice Emeritus of Finance at Yale School of Management.

Professor Ibbotson researches various financial topics and is a regular contributor and editorial board member to trade and academic journals.

Professor Ibbotson served on numerous boards, including Dimensional Fund Advisors’ funds. He frequently speaks at universities, conferences, and other forums. He received his bachelor’s degree in mathematics from Purdue University, his MBA from Indiana University, and his PhD from the University of Chicago where he taught for more than 10 years and served as executive director of the Center for Research in Security Prices.


Questions from audience, with responses from Professor Roger Ibbotson

Does GDP per capita data have an adjustment for inflation?


How do you rate the possibility of a major ‘collapse’ of a high energy and technology-dependent society?

Computers, electrical systems, etc. do crash and may be vulnerable to weather, wars, terrorists, hacks, etc. A high-tech society needs back-up systems and separation barriers to avoid contagion. Yes, ‘collapses’ are possible. So far humanity has been able to recover from even the most major upheavals.

Are humans changing the global environment faster than even we can successfully adapt to?

Yes, it is hard to know what is “under the hood.” We have to rely on specialists in many areas. Although often I cannot personally adapt to much of the changing environment, humanity seems to be adapting pretty well.

Thinking about some of the charts you presented made me remember another chart I’ve seen – from Ray Kurzweil, the “Prophet of the Singularity.” I think some critics of Kurzweil might say there’s no way we can expect technology to keep accelerating the way it has over the past two hundred years. How would you respond to followers of Kurzweil who expect, more or less, that ever-accelerating technological development is more or less guaranteed and can be taken for granted?

I do believe that technology grows exponentially but may not be ever accelerating. Some have argued that even as technology has increased, the benefits have increased at a slower rate, e.g., getting electricity, a telephone, TV, and a car may have been bigger marginal benefits than getting a computer, an iPhone and the internet.

What do you think of the degrowth movement? Can humanity thrive without economic growth?

I do not think we need population growth. I think we can thrive with per capita growth, which I believe is inevitable as we accumulate knowledge from one generation to the next. However, as population growth disappears, there will be transitions as the population ages.

Is medicine anti-evolutionary, particularly efforts to decrease aging?

Darwin was concerned with reproduction and not really with longevity, especially if it just extends life beyond reproductive ages. Of course, a large group of “old” people will increase the overall population and will have uncertain impacts on the economy.

Is our evolved immune system a significant factor in our higher survivability?

Yes. But humans are no longer evolving in biological positive ways. Meanwhile the various types of plagues continue to evolve. We have to adapt with vaccines, medicines, artificial parts, etc.

I think you said early in the presentation that the human animal is no longer genetically adapting. Is that true? Do you have a reference on this matter?

I do not know of a reference, as I think it just my personal insight. Darwin thought we evolve through statistical survival rates, and when our offspring all survive, it is no longer “survival of the fittest’ or really the most adaptable. I am just applying logic to the data, using Darwinian interpretations.

Does Professor Ibbotson feel optimistic that we can right this ship around?

I think humans will continue to adapt to the changing environment, with ever higher per capita income. It is all the other species of the world that I am most concerned about. We have to learn to treat our domesticated animals better. As for the wild species, developed countries need to lower their environmental footprint, and less developed counties need to lower their fertility rates (which will help them become developed). I am optimistic that we are moving in the right direction, but probably not fast enough.

The following answers are by Marian Starkey, VP for Communications:

Can you address the impact of delaying childbirth by a few years, even for a given birthrate?

Delaying childbirth lowers total fertility rates in two ways:

  • It shortens the period of time during which women are physically able to conceive. This is especially important regarding child/early marriage. For example, if a girl gets married at 15 and begins her childbearing then, she’ll have 3+ decades during which she could become pregnant. If she doesn’t have her first baby until age 25, she’ll have 10 fewer years for childbearing.
  • It creates a tempo effect by lengthening generations and reducing the compounding effect of multiple age cohorts having babies at the same time. Here’s a paper that seems to do a good job explaining this phenomenon.

How can we reduce the population without causing fundamental pushback from disagreeing people? 

There will always be people who are alarmed by fertility decline and want birth rates to increase, but they have little effect on how people actually make decisions around their own childbearing. For example, South Korea has the lowest total fertility rate in the world, at 0.78 births per woman. The South Korean government is extremely concerned about this and has spent hundreds of billions of dollars trying to encourage higher fertility, to no avail. A similar scenario has played out in Japan, Singapore, and, more recently, China.

The countries with the highest proportion of Catholic people have some of the lowest fertility rates in the world: Italy, Spain, Portugal, Poland, etc. This demonstrates how little effect religion has on people’s fertility behaviors in places where they have access to appropriate and affordable contraception.

In its literature, Population Connection often notes the objectives of population control but does not outline the specifics of how to achieve those objectives. We know what the result of such efforts should be, but not the methods needed. 

Population Connection vehemently opposes any sort of coercive or draconian methods, which is what the term “population control” has come to mean over the last few decades. Rather, we, along with every population organization I know of, believe that the way to stabilize population is to make voluntary family planning education and services universally accessible so that people can make informed choices for themselves about whether, when, and with whom to have children. In every place on earth where affordable and appropriate contraceptives are reasonably easy to obtain, fertility rates have fallen to replacement rate or lower.

How best to turn public opinion toward the Population Connection viewpoint?

As far as family planning and reproductive health go, the American public is already there. People in this country overwhelmingly believe that contraception and abortion should be legal and accessible, despite the decisions politicians make in Congress and in state houses.

But most people in the U.S. don’t know that population growth is a problem that exacerbates just about every environmental challenge. Our Population Education program aims to change that, reaching some 3 million K-12 students a year with our population literacy lesson plans. We also do informational outreach through our quarterly magazine, blog, social media, and earned media.