July 14, 2026 (menalive.com)
Heated disagreements about sexuality and gender are everywhere these days. As an evolutionary-trained clinician who specializes in gender-specific medicine and men’s health, I have been helping individuals and couples improve their love lives for more than fifty years. I recently interviewed Dr. Nathan L. Lents about his latest book, The Sexual Evolution: How 500 Million Years of Sex, Gender, and Mating Shape Modern Relationships. I found the book to be enlightening, engaging, and downright fun to read.
I have often found resistance in some circles when I talk about the biological and evolutionary roots of who we are as males and females. Some people fear that differences will be used, as they have in the past, to restrict people’s freedom and to keep some locked into boxes that are rigid and unchanging. That does not have to be the case as Dr. Lents points out so effectively.
Joan Roughgarden, Professor emerita of biology at Stanford University, and author of Evolution’s Rainbow had this to say about The Sexual Evolution:
“A lot of people seem to think they know what science says when it comes to sex. Well, Nathan Lents has news for them. Read this book — it’s fascinating, charming, and eye-opening, with lovely ink drawings that bring the animals in its pages to life. It dispels misconceptions about life in the animal kingdom and our place in it, but most important, it shows clearly that nature’s beautiful sexual diversity extends to all living things — especially humans.”
“In just two generations, the sexual landscape has completely changed throughout most of the developed world, and so it is no surprise that many people find all of this terribly unsettling,” says Dr. Lents. “What is surprising to me however, is how little the biology and natural history of sex has factored into the public conversation. I assert that this moment of sexual turmoil is actually a rediscovery of the much more expansive relationship with sex that our ancestors once had and that other animals enjoy today.”
I grew up in southern California and spent endless hours wandering in nature. I was a biology major in college and found the world of plants and animals fascinating. As a marriage and family counselor I have found that my understanding of biology and evolution is invaluable in helping me support my client’s desire to have a wonderfully passionate sex and love life.
In a recent article, “This Truth About Males and Females Will Change Your View of Sex, Love, and Life Forever,” I described the work of my colleague, Michael Gurian, who has been reporting on male/female differences in brain function for decades. In a video blog, he shared the research that has been going on for more than 40 years and the evidence from a new study that shows brain differences, in utero, long before the effects of gender socialization.
If there was one thing Dr. Lents wanted people to take away from reading his book, it is the value of diversity in the lives of all living things.
He said that in the modern world, much of how we express our sexuality, and how we form our sexual relationships, stems from cultural constructions, not innate biological wiring. Even a cursory glimpse of the sex lives of other animals demolishes any notion that sexual activity is narrowly purposed toward procreation. Biologists have discovered an ever-expanding list of reasons that animals have sex with each other. Animals use sex for bonding, social cohesion and alliance building. They use sex deceptively, competitively and financially. They even have sex for the same reason that we most often do it: just for the fun of it.
Moreover, in no other species but humans is sex rigidly restricted by broad constructions such as heterosexuality and sexual monogamy, nor was it so restricted for most of the history of our own species. As humans explore this supposedly new sexual territory, we can look to our animal cousins for guidance on how to manage this minefield of social upheaval.
Not only will an understanding of our evolutionary diversity help improve our love lives, it may very well be the key to our survival. You don’t have to be a trained scientist to recognize that our human species is out of touch with the laws of nature. The burning hot temperatures we are experiencing all over the world is one reminder of the risk we are facing as humans continue to undermine our connections to the Gaia and all her diverse life forms.
As Thomas Berry warned us:
“We never knew enough. Nor were we sufficiently intimate with all our cousins in the great family of the earth. Nor could we listen to the various creatures of the earth each telling its own story. The time has now come, however, when we will listen or we will die.”
There is still time to listen and learn. If you would like to get more information about Nathan H. Lents, you can do so here: https://thehumanevolutionblog.com/. He told me he’s interested in hearing from people and he reads all emails people send.
If you are interested in my own work, please visit me at https://menalive.com/.
Jed Diamond
Founder and VHS (Visionary Healer Scholar) of MenAlive
