HC1 EP What is evolution? 02/09/2025
EP → about our deep time
We as humans have been around for 2 to 3 million years. It was a completely different
environment back then. Our ancestors' lifestyles still influence what we fear today, how we
think, what we want, and so on.
- 99% of our time here (as humans) was spent in a completely different environment.
This has a profound impact on how we are, think, and live now.
Hominoid (any great ape, living or extinct, including humans).
→ The skull reveals a lot of information about the being.
- Gender → Men have thicker skulls and bones.
- What did he eat?
- How did he get his injuries? → First murder victim found.
- His wounds partially healed → shows that someone cared for him.
- Found among many bones, a grave.
- So even hominoids had rituals.
Poll question 1: Why do (most) humans like eating foods high in sugar and fat?
Because in ancestral environments, preferring calorie-rich foods increased survival chances.
- Food was scarce, and you had to grab all the calories you could. This craving is
especially noticeable among young people. The most caloric food back then was
honey. We don't have impulse control for that. Marketers exploit it.
Evolutionary psychology: Natural and sexual selection
We dig one level deeper than psychologists. Why did it evolve, what is the evolutionary
advantage? What is the function? Psychologists only look at the how.
Parental investments are quite new. They don't really exist (or haven't existed for very long)
in the animal kingdom.
We'll also look at homosexuality, language, religion, corporations, and rituals—how do you
view them from an evolutionary perspective? But also, why do we sometimes take such risks
(to be heroic, or hospital workers)? Why do we have leaders and followers? Why is there a
dark side, such as violence against women? What is the evolutionary function of all this?
- Why do people do these things?
- Can we explain them with existing theories in psychology and the social sciences?
- Could we gain insights by thinking about humans as a biological species, subject to
the same environmental pressures as other animals?
Evolutionary psychology
Evolutionary psychology is the study of human behaviour, affect, emotion and cognition from
an evolutionary perspective. Using evolutionary theory to understand why the human mind
works this way and how it has been designed. It means viewing humans as part of the
animal kingdom, subject to the same laws of evolution, natural selection, etc.
→ This might seem contentious! but there is really no plausible alternative!
,Learning goals
- Be able to articulate what is evolutionary psychology
- Be able to identify the three essential ingredients of evolution via natural selection
- Understand the difference between natural and sexual selection
- Be able to identify why Neanderthals went extinct
- Know the history of evolutionary psychology
- Be able to list procedures for identifying adaptive problems
- Be able to identify common misunderstandings about evolutionary theory and
evolutionary psychology.
Own nature
Every species, including humans, has its own nature. This is a constellation of traits typical
for that species.
- For example, dogs and cats live very differently. Dogs eat everything quickly (they
are descended from wolves who are social animals that live in packs and therefore
have to compete for food), while cats eat quietly (they are solitary animals, they
compete outside their territory but not within it).
Humans have this too. You can put us in a house, but our brains originate from a kind
of migration across the earth.
Evolution of traits - Pre Darwin
Jean-Baptiste Lamarck (1744-1829)
1. Inheritance of acquired characteristics
2. Use and disuse of traits (e.g., muscles)
3. The come-back kid: Epi-genetics
A giraffe eats food that grows high. Jean Baptiste thought that all this stretching naturally
lengthened the neck and that this was passed on. So, if we exercised, we'd pass those large
muscles on to our children. That's not true.
Non-scientific theories
- Creationism: a supernatural force created us.
- Seeding theory: life from another planet.
→ There is no scientific basis for either. The only thing that can describe our complex
existence is natural selection.
Charles Darwin (1809-1882)
- Charles Darwin: The voyage of the Beagle (1831- 1836)
- He was a scientist on a boat. He took specimens everywhere. He also
stopped at the Galapagos Islands, where he shot many birds. He noticed that
they all had different beaks. They had a lot in common, but there were also
differences. When he returned, he saw the connection between the island, the
type of food, and the beak. There was an original and some adaptations.
- He grew up in the Victorian era, very religious. He proposed an
alternative theory. He then received a letter from Wallace, and 20
years later they wrote together about natural selection.
- Book “On the Origin of Species” (1859)
,Natural selection and the survival of the “fittest” → most adaptable
Darwin quote: “As many more individuals of each species are born than can possibly
survive; and as, consequently, there is a frequently recurring struggle for existence, it follows
that any being, if it vary however slightly in any manner profitable to itself, under the complex
and sometimes varying conditions of life, will have a better chance of surviving, and thus be
naturally selected. From the strong principle of inheritance, any selected variety will tend to
propagate its new and modified form.” → Later: Survival of the fittest
Charles Darwin: Great grandfather of evolutionary psychology
“In the distant future I see open fields for far more important research. Psychology will be
based on a new foundation”
How does evolution through natural selection work?
Poll question 2: Cutting off the tail of a mouse has what effect on the next generation(s)?
- None (unless it kills the mouse before it reproduces), nothing you do during your life
changes your DNA, so you don't pass it on.
3 components of natural selection
1. Variation → tall, short, female, male
2. Inheritance → some trades you inherit, for example how tall you are
3. Sélection → de eigenschap die overlevingskansen verhoogt overwint
Back to the giraffe example:
One baby giraffe is born with a longer neck than normal. It can grab food that's too high for
the others. Its siblings with short necks die. The one with the long neck does reproduce, and
its offspring also have long necks. Ultimately, this trait is passed on.
- There is individual variation in traits. (A longer neck.)
- Some trait variants allow their bearers to better compete for resources. (More and
better leaves.)
- If these traits are inheritable then they are passed on from generation to generation.
(Long neck is heritable.)
- The result: individuals of a species become better adapted to their environments over
time. (Over time all giraffes are born with a long neck.)
→ Natural selection, the only mechanism we know about that explains how species come
about, how species evolve and how life gets more and more complex over time.
So that's basically when we think of a trait, like the giraffe's neck, that has gone through
fixation (→ all babies that are being born have this trait), that's when we call it an adaptation.
= The functional solution to a problem that a species encounters in a particular physical
environment (could also be social environment)
A mechanism for evolution via natural selection: the gene
Gregor Mendel (1822-1884) → An experiment with peas. He discovered that traits are
passed down through dominant and recessive alleles, laying the foundation for modern
genetics and explaining how variation is inherited.
How do the genes get mixed into a new set of genes? → Sex.
, Modern synthesis in biology: DNA discovery
Crick & Watson, 1953
1. Mixing parental genes (sex)
2. Recombination of genes (double helix)
3. Random mutations → could lead to adaptations
98% of the genes (building blocks) of a human are the same as a chimpanzee.
- Chimpanzees and humans are closer related than chimpanzees and gorillas.
-
Common ancestor with the chimpanzees → Why did we split?
- Climate change, forests were declining. → A different way of life prevails.
EP → about our deep time
We as humans have been around for 2 to 3 million years. It was a completely different
environment back then. Our ancestors' lifestyles still influence what we fear today, how we
think, what we want, and so on.
- 99% of our time here (as humans) was spent in a completely different environment.
This has a profound impact on how we are, think, and live now.
Hominoid (any great ape, living or extinct, including humans).
→ The skull reveals a lot of information about the being.
- Gender → Men have thicker skulls and bones.
- What did he eat?
- How did he get his injuries? → First murder victim found.
- His wounds partially healed → shows that someone cared for him.
- Found among many bones, a grave.
- So even hominoids had rituals.
Poll question 1: Why do (most) humans like eating foods high in sugar and fat?
Because in ancestral environments, preferring calorie-rich foods increased survival chances.
- Food was scarce, and you had to grab all the calories you could. This craving is
especially noticeable among young people. The most caloric food back then was
honey. We don't have impulse control for that. Marketers exploit it.
Evolutionary psychology: Natural and sexual selection
We dig one level deeper than psychologists. Why did it evolve, what is the evolutionary
advantage? What is the function? Psychologists only look at the how.
Parental investments are quite new. They don't really exist (or haven't existed for very long)
in the animal kingdom.
We'll also look at homosexuality, language, religion, corporations, and rituals—how do you
view them from an evolutionary perspective? But also, why do we sometimes take such risks
(to be heroic, or hospital workers)? Why do we have leaders and followers? Why is there a
dark side, such as violence against women? What is the evolutionary function of all this?
- Why do people do these things?
- Can we explain them with existing theories in psychology and the social sciences?
- Could we gain insights by thinking about humans as a biological species, subject to
the same environmental pressures as other animals?
Evolutionary psychology
Evolutionary psychology is the study of human behaviour, affect, emotion and cognition from
an evolutionary perspective. Using evolutionary theory to understand why the human mind
works this way and how it has been designed. It means viewing humans as part of the
animal kingdom, subject to the same laws of evolution, natural selection, etc.
→ This might seem contentious! but there is really no plausible alternative!
,Learning goals
- Be able to articulate what is evolutionary psychology
- Be able to identify the three essential ingredients of evolution via natural selection
- Understand the difference between natural and sexual selection
- Be able to identify why Neanderthals went extinct
- Know the history of evolutionary psychology
- Be able to list procedures for identifying adaptive problems
- Be able to identify common misunderstandings about evolutionary theory and
evolutionary psychology.
Own nature
Every species, including humans, has its own nature. This is a constellation of traits typical
for that species.
- For example, dogs and cats live very differently. Dogs eat everything quickly (they
are descended from wolves who are social animals that live in packs and therefore
have to compete for food), while cats eat quietly (they are solitary animals, they
compete outside their territory but not within it).
Humans have this too. You can put us in a house, but our brains originate from a kind
of migration across the earth.
Evolution of traits - Pre Darwin
Jean-Baptiste Lamarck (1744-1829)
1. Inheritance of acquired characteristics
2. Use and disuse of traits (e.g., muscles)
3. The come-back kid: Epi-genetics
A giraffe eats food that grows high. Jean Baptiste thought that all this stretching naturally
lengthened the neck and that this was passed on. So, if we exercised, we'd pass those large
muscles on to our children. That's not true.
Non-scientific theories
- Creationism: a supernatural force created us.
- Seeding theory: life from another planet.
→ There is no scientific basis for either. The only thing that can describe our complex
existence is natural selection.
Charles Darwin (1809-1882)
- Charles Darwin: The voyage of the Beagle (1831- 1836)
- He was a scientist on a boat. He took specimens everywhere. He also
stopped at the Galapagos Islands, where he shot many birds. He noticed that
they all had different beaks. They had a lot in common, but there were also
differences. When he returned, he saw the connection between the island, the
type of food, and the beak. There was an original and some adaptations.
- He grew up in the Victorian era, very religious. He proposed an
alternative theory. He then received a letter from Wallace, and 20
years later they wrote together about natural selection.
- Book “On the Origin of Species” (1859)
,Natural selection and the survival of the “fittest” → most adaptable
Darwin quote: “As many more individuals of each species are born than can possibly
survive; and as, consequently, there is a frequently recurring struggle for existence, it follows
that any being, if it vary however slightly in any manner profitable to itself, under the complex
and sometimes varying conditions of life, will have a better chance of surviving, and thus be
naturally selected. From the strong principle of inheritance, any selected variety will tend to
propagate its new and modified form.” → Later: Survival of the fittest
Charles Darwin: Great grandfather of evolutionary psychology
“In the distant future I see open fields for far more important research. Psychology will be
based on a new foundation”
How does evolution through natural selection work?
Poll question 2: Cutting off the tail of a mouse has what effect on the next generation(s)?
- None (unless it kills the mouse before it reproduces), nothing you do during your life
changes your DNA, so you don't pass it on.
3 components of natural selection
1. Variation → tall, short, female, male
2. Inheritance → some trades you inherit, for example how tall you are
3. Sélection → de eigenschap die overlevingskansen verhoogt overwint
Back to the giraffe example:
One baby giraffe is born with a longer neck than normal. It can grab food that's too high for
the others. Its siblings with short necks die. The one with the long neck does reproduce, and
its offspring also have long necks. Ultimately, this trait is passed on.
- There is individual variation in traits. (A longer neck.)
- Some trait variants allow their bearers to better compete for resources. (More and
better leaves.)
- If these traits are inheritable then they are passed on from generation to generation.
(Long neck is heritable.)
- The result: individuals of a species become better adapted to their environments over
time. (Over time all giraffes are born with a long neck.)
→ Natural selection, the only mechanism we know about that explains how species come
about, how species evolve and how life gets more and more complex over time.
So that's basically when we think of a trait, like the giraffe's neck, that has gone through
fixation (→ all babies that are being born have this trait), that's when we call it an adaptation.
= The functional solution to a problem that a species encounters in a particular physical
environment (could also be social environment)
A mechanism for evolution via natural selection: the gene
Gregor Mendel (1822-1884) → An experiment with peas. He discovered that traits are
passed down through dominant and recessive alleles, laying the foundation for modern
genetics and explaining how variation is inherited.
How do the genes get mixed into a new set of genes? → Sex.
, Modern synthesis in biology: DNA discovery
Crick & Watson, 1953
1. Mixing parental genes (sex)
2. Recombination of genes (double helix)
3. Random mutations → could lead to adaptations
98% of the genes (building blocks) of a human are the same as a chimpanzee.
- Chimpanzees and humans are closer related than chimpanzees and gorillas.
-
Common ancestor with the chimpanzees → Why did we split?
- Climate change, forests were declining. → A different way of life prevails.
