Michael Soule' © Brian Miller

Michael Soulé’s Unpublished Thoughts on Sin and the Human Condition.

Featured Image: Michael Soulé © Brian Miller

Shared by Brian Miller and other Friends of Michael

These thoughts are a brief summary of what Michael was thinking on Sin and Conservation.  They also include some thoughts from private conversations we had over the years.  His many, and influential, publications are well known.  We want to keep alive these thoughts from his last writings – which he hoped would become a book that would help inform efforts to end the extinction crisis.

Scale is one of the most difficult concepts in ecology.  Two people can be arguing a point, and sometimes both are right because they are thinking at different scales.  Another misunderstanding comes when someone extrapolates the effect at one scale to a different scale.  This can lead to false dualisms, and nearly all dualisms are false.  Fire can keep you warm and cook your food.  At a different scale fire can destroy large areas and take human lives.  Good and bad can be situational.

So can sin.  Historically, people have recognized “seven deadly sins”, which are also called Horace’s Heptad.  Horace laid them out about One Century BC, and the Desert Fathers (early communities of Christian theorists) adopted them.  Those sins are inclinations that can be good or bad, depending on the situation.  At least five of those “sins” are firmly based in evolution.  Greed, anger, lust, gluttony, and sloth were key parts of sexual selection going all the way back to the earliest forms of life. Those five are embedded in the shared DNA of all species.  Pride and envy are more recent and perhaps cultural.  We can add denial and despair to the cultural part of the Heptad.

In a nutshell, the five were key to survival and reproduction.  Fitness in any species is defined by the contribution of genes you can leave in the next generation.  For example, gluttony was adaptive because food sources for many species are scattered and irregular.  The survival strategy is to consume as much as you can when you have the opportunity because the next meal may not present itself for a while.  Some reptiles and amphibians can eat up to 70% of their body weight in one sitting. Physical sloth helped an individual recuperate energy expended by gathering food.  Greed collected what one needed to survive.  Anger spurred one into action; and together with greed, anger protected what one needed to survive.  So, the five are adaptive in the natural world going back to the earliest forms of life.  They help an individual to survive and reproduce.  Reproducing increases fitness.

The key for humans and nature is that 10,000 years ago greed, lust, gluttony, sloth, and anger increased our individual fitness.  The question now is: Can the planet survive the deadly sins at present human population levels, economic affluence, and technological level of sophistication?  Planetary change is happening fast, perhaps 100 times as fast as just a century ago.

It took humans 200,000 years to reach a population of one billion.  It took 200 more years to reach 7 billion.  We are now at 7.8 billion, with predictions of reaching 10 billion by 2050.  The rate of increase has been clearly exponential.  Unfortunately, the rate of increase for resources humans use has been largely linear, and in relation to increasing the amount of area necessary to produce our needs.  Right now, humans use over 70% of the ice-free land for food, fabric, building materials, etc.[1]  Slightly over 40 % of ice-free land goes directly to food production.[1] [2]  We use about 50% of the planetary fresh water, and about 80% of our water use is for agriculture.[2]  In some places, humans are withdrawing four to six feet a year from the Ogallala Aquifer, while nature is putting back half an inch.[3] The Aquifer is already dry in some parts of Texas and Kansas.[3]

By 2050, we may reach 10 billion people, with a predicted per capita increase in buying power of 150%.[4] The amount of land needed to feed us will double, and freshwater use will increase by 55%.[2] Our food production causes 20% of the annual contribution of carbon to the atmosphere.[2]  The irony is that humans rely on a stable interglacial climate for food production, but our carbon contribution makes weather more and more erratic, potentially diminishing future food production.

Ninety-six percent of the global biomass of mammals is human and our domesticated animals.[5]  The amount of agriculture to feed us has created 400 dead zones in the ocean.[2]  The rate of tropical deforestation is accelerating. Ocean life is already badly depleted.  If we reach 10,000,000,000 in 2050, what will be left for other forms of life?

Added to growing human numbers is consumption.  More people mean more consumption, but per capita consumption also increased– by a factor of 40 from 1900 to 20006.  The assumption of constant growth is false.[7]  We cannot constantly grow with our limited resources.  The Laws of Thermodynamics cannot be violated.  Up to now we have been able to switch to a different resource when the one we had used expired.  But we live on a globe and if we keep gobbling up whatever is in front of us, eventually we come to our back door.

Right now, it takes about one year and seven months to replenish what humans use in a year.[2]  That is not a good strategy for long-term sustainability.  All energy comes to Earth in the form of sunlight.  We have been able to extend our growth by using past sunlight in the form of fossil fuels.[7].  It takes millions of years to convert organic matter to oil fuels.  They are not renewable.

So back to scale, I could swat at a mosquito that was biting me (only females draw blood–males eat nectar and pollen and thus pollinate).  This is very different from trying to genetically alter mosquitos out of existence.  Bats would be very unhappy if we did so.  Another example is that jellyfish were clogging a nuclear power facility to the point that the facility had to temporarily close. The anthropocentric answer was to create robo-choppers that could chop jellyfish into pulp to the tune of 900 kilograms per hour.[8] That is different from swatting away a jellyfish while swimming. Sea turtles would not happy about the robo-choppers.  The paradigm of constant growth is killing nature.  We cannot continue to use 1.7 planets worth of resources.  The only way we can grow our numbers and consumption is to take more from nature and other species. Eventually we will reach a ceiling, and the harmful effects of constant growth will fall on us.  We are clever but not very smart.

What is an acceptable number of humans that can live well and still allow a significant portion of the planet to exist as nature?  Many figures say around two to four billion.[2]  The key to reducing human numbers is empowering women, family planning, and readily available contraception.  When women are educated, and have a place in society, birth rates and poverty are reduced.  In Africa, a woman who didn’t go to school averages 5.4 children.[2]  With a high school diploma, the number of children per woman is 2.7.  With a college degree the rate is 2.2.  A replacement rate of 2.1 (or lower) with a longer generation time will lower population numbers over time. Available contraception will reduce unwanted pregnancies. Unfortunately, there is heavy political and religious opposition to empowering women.  Some societies want to keep women barefoot and pregnant.

We conservation biologists are not optimistic, particularly in the short-term.  Optimism and pessimism are rational responses to data analysis.  But, we have hope.  Hope is irrational.  You see a trend and try to change it.  Hope has to be combined with passionate action. Nelson Mandela thought he might be in prison for life, yet he never abandoned hope.  If hope is combined with mental sloth it leads to inaction.  Inaction implicitly supports the status quo.

For example, someone on Easter Island cut down the last tree, knowing that it was the last tree.  They did it with the faith that their gods would take care of them.  That is how we can add denial to Horace’s Heptad.  Many have faith that we can persist no matter what (mental sloth) and deny that our actions can be harmful (climate change, extinction, Covid-19).  Those imbued with feelings of human exceptionalism (anthropocentrism) put blind faith in technology.  If fresh water is gone, then turn to desalinization. Global warming can be countered by shooting sulphur dioxide into the atmosphere.  The list goes on.

We must counter denial and delusion, and it will take a diverse group of people and skills.  Students often ask “what can I do?”  Michael says, “Do what you do best.”  Maybe you wanted to be a biologist, but you didn’t like organic chemistry or statistics.  You can become a passionate lawyer defending nature against its enemies.  Maybe you are an artist bringing a message for nature to the public.  Maybe you study the political process and know how to get legislation passed.  Maybe you are an activist and interlocutor for nature. Conservation is an inter-disciplinary effort.

Michael was one of the best minds of this generation.  He set the stage for the conservation movement of today.  Never give up on the dream.



1.Baillie, J.E.M., Griffiths, J., Turvey, S.T., Loh, J. & Collen, B. (2010). Evolution lost: status and trends of the world’s vertebrates. London: Zoological Society of London.

2. Crist, E., C. Mora, and R. Engleman.  2017. The interaction of human population, food production, and biodiversity protection. Science 356, 260 –264.

3. J.B. Little. 2009. The Ogallala Aquifer: Saving a vital U.S. water source.  Scientific American, Special Edition 19: 32-39. http://www.scientificamerican.com/article/the-ogallala-aquifer/5.

4. Tilman, D. (2012). Biodiversity and environmental sustainability amid human domination of global ecosystems. Daedalis J. Am. Acad. Sci. 141, 108–120.

5. Yinon, M., Bar-On, R. Philips, and R. Milo.  2018.  The biomass distribution on Earth.  PNAS 115: 6506-6511

6.Wright, R. (2005). A short history of progress. New York: Carroll and Graf Publishers.

7. Czech, B. (2013). Supply shock: economic growth at the crossroads and the steady state solution. Gabriola Island: New Society Publishers.

8. Eileen Crist. 2014. Confronting Anthropocentrism.  https://www.youtube.com/watch?v=pZkFj9uPKXo&t=89s


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