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Greetings this presentation is called what is an ultimate or evolutionary question
and what we're getting at with that
is a distinction
between what are called proximate causes and ultimate causes
or proximate explanations and ultimate explanations
and you'll read about that more this week
in chapter one of Meeting at Grand Central and you also read about it a little bit last week
so we're going also discuss that in this presentation because it's a key distinction
that's generally made at the start of all introductions to behavioral ecology
and traces back to two classic papers in the early 1960s
one by Niko Tinbergen in 1963
on the Aims and methods of ethology
ethology refers to the field study of animal behavior
and the second paper was by Ernst Mayr
and titled cause and effect in biology
and each of these papers had a variety of things going on but they had a shared argument
and the shared argument was a defense of the legitimacy of evolutionary questions
So among other things Tinbergen discusses - and his paper's kind of complicated because it
does a lot of things and doesn't necessarily focus in on this distinction, but it addresses it -
it was a tribute to another early ethologist, named Konrad Lorenz,
it also was a critical review of
studies of animal behavior up until the 1960s and what they should do differently
and among the things that Tinbergen stressed was importance of direct field observations
along with experimentation
and given that he was stressing an evolutionary perspective this might seem puzzling - How you observe evolution
and the key point that Tinbergen made in relation to this
was that while you couldn't observe what happened in the past
you can observe the survival value of current behavior and interpret that in relation to natural selection.
and this came to be a central premise
of behavioral ecology -
and that's the study of animal behavior from an evolutionary perspective.
So this is why Tinbergen is so often of emphasized.
He provided that central premise.
Mayr also had a number of topics to address
He wanted to differentiate between causality in classical mechanics, that you might learn in introductory physics,
as opposed to biology. He wanted to argue that teleology had nothing to do with evolution -
this means that there's some greater design, or unfolding purpose.
And he stressed that evolutionary theory couldn't produce predictions about the future,
and this too makes it different from physical theory.
In making those arguments he also came to stress a key distinction,
and this was a distinction between ultimate and proximate explanations.
And what he was getting at
he set it out through an example
of a warbler on his deck, and posed a question: well, how could we explain why this warbler
left to fly south on August 25?
So here's a yellow warbler which probably looks like the one that Mayr observed on his deck.
And he said, well we might say that the warbler is responding to the length of the day, which is getting shorter
or the temperature which is getting colder
and also perhaps the direction and the intensity of the wind, so was responding to these environmental cues
and on 25th of August these environmental cues came into alignment
and that provoked the warbler to head south. And he argued that we can also come up with
other explanations for why the warbler was going to leave
And one would be that if it stayed it would starve to death,
and he argued that if we say this, we have to say that it's adapted to departing
probably through some kind of a genetic
evolution
which leads it to be sensitive to the length of day, and temperature and the winds,
and leads it to choose a date to depart before the food supplies decline
so these proximate causes can be provided by a functional biology
But ultimate causes are why questions
and evolutionary biology provides these questions.
So this is an effort to explain
how the warbler came to be adapted to leave on that day it's not how it happens physiologically
it's why it happens
so a proximate explanation is the answer to a how question
whereas an ultimate explanation is an answer to a why question
You might wonder why in the 1960s you have two leading biologists arguing for the importance of an evolutionary perspective
after all the origin of species was published in 1859
and then after much strife genetics was united with evolutionary biology in the 1930s in what's called the modern synthesis
so by the 1960s evolutionary biology had been around a long time.
But despite that you had an exclusion of evolutionary questions
from a great deal of teaching and research in biology for many decades
and you might say, well, what could you teach about biology without evolution? And you can actually talk about quite a lot.
You can go over Linnaean taxonomies.
you can go over structural anatomy and functional physiology
of the structure and and workings of organisms
you can go over chromosomes and DNA
and you can discuss Mendelian genetics. So there's quite a lot that you can go over and this
is what Mayr meant by functional, descriptive biology
It's essential and it provides a lot of answers
But his argument is evolutionary biology then integrates and changes how we understand all of this
from systematics and classification to genetics
So let's take an example of this idea that an evolutionary perspective changes things, or that ultimate questions are different
and we'll take our example from 169 of mothers and others
this is further along in the book
than we are right now
but when you get there Hrdy will discuss how
hormones impact human behavior
and she notes that men as well as women
undergo alterations in their physiology
when they hold babies and are around babies and these the physiological alterations tend to lead us to
behave in more nuturant ways
This has to do with prolactin and serotonin and other hormones.
So functional biology can explain how that happens
that would be the study of how those hormones change
and how they change our behavior
But evolutionary biology tries to explain why that happens -
why would both men and women be altered by exposure to babies? Why would men
become more nurtuant when they hold babies, as well as women?
And this is then the heart of this proximate- ultimate distinction, the proximate explanation is provided by functional biology
the ultimate explanation is provided by evolutionary biology.
So in terms of this idea that evolution changes everything we can also look take an evolutionary perspective on ontogeny
and that's how we develop, and this is increasingly discussed under what's called life history theory
life history theory asks why, why our adolescence is the length that it is?
why we reach *** maturity when we do? and why we reproduce at the age that we do?
Why we go into senescence when we do? So it tries to explain how our life history patterns evolved
and one way we can do that
that's interesting is to compare humans with other primates. This chart compares humans to chimps and gibbons and macaques and lemurs
and you'll notice we are most similar to the chimps -
the second column from the right
humans are the column furthest to the right
but if we compare humans to chimps there's two key differences.
The first is that the childhood dependency of humans is longer
so humans have the longest dependency of any primate and this is a time when we need parental care
when our parents have to invest in us.
And humans also have extended post reproductive lives - that means we continue to live
for many years after we reproduce last and this is most interesting for women -
men can continue to conceive children into their seventies and eighties
but women go through menopause and then no longer conceive children
yet women generally live longer than men in among humans
and so the question is why are there these long live grandmothers? on the one hand,
and maybe, this is related to this long childhood dependency?
and how costly human offspring are?
and this is called the "grandmother hypothesis"
so it's an evolutionary hypothesis to explain why there are grandmothers
why grandmothers are so prominent in human societies
and argues grandmother's provide assistance to their daughters and this leads to greater survival of their grandchildren
and given this, humans have evolved this long post reproductive
period of our lives,
as we've extended our dependency.
So this gives us an evolutionary way to ask ultimate questions about ontogeny or development
and in doing that we used a phylogenetic perspective
and that means we're looking comparatively across related species that share common ancestry with us
and we're interested in both what's conserved - how we're similar to those other species
that also what's different or derived
so derived traits are traits that are distinctive - that take a different turn in humans
and really the only way we can identify what's derived and what's
conserved, is through comparisons, and the most informative comparisons are those that are phylogenetically proximal,
that means the most telling comparisons are usually to species that are most closely
related to us and Sarah Hrdy will make a lot of phylogenetic comparisons in her book
which is one reason why I assign it. So if we think about this class,
and if you're taking a course that focuses on descriptive or functional biology
you might not ever get to ultimate questions
in contrast to that in this class we're going to focus most of our attention on ultimate
approaches to human behavior
and we'll spend relatively little time on proximate biology.
So you're not going to learn a lot of functional biology in this class.
Instead you'll learn a lot of ultimate
evolutionary perspectives.
so now we come to the helicopter professor page, where I try to point out some key questions you should be able to answer
based on this presentation
they both made this argument
what's an example of that?
so what is that central premise?
and if you can answer those questions you'll be prepared for the quiz
and thank you for listening