Road Map. Evolution: variation + selection = adaptation example: LDH in killifish Evolved behaviors Tropisms in bacteria & fruit flies Gibbon songs Instinctive learning Zebra finches, humpback whales Culture as evolution? “memetics” vs. genetics arguments pro and con
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variation + selection = adaptation
example: LDH in killifish
The mummichog B locus for lactate dehydrogenase (LDH) has two common alleles, LDH-Ba and LDH-Bb. Catalytic efficiency varies with temperature: the bb genotype “wins” at lower temperatures, while the aa genotype “wins” at higher temperatures.
In the Gulf of Maine, nearly all mummichogs have the
genotype bb at the LDH-B locus. Off South Carolina, the aa genotype rules. In between, it’s in between.
Fruit flies show natural variation in preferences
Pupae hatching in experimental “habitat maze”
Among the apes, only gibbons and humans have pair bonding.Also, only gibbons and humans sing…
All species of gibbons are known to produce elaborate, species-specific and sex-specific patterns of vocalisation often referred to as "songs" (Haimoff, 1984; Marshall & Marshall, 1976). Songs are loud and complex and are mainly uttered at specifically established times of day. In most species, mated pairs may characteristically combine their songs in a relatively rigid pattern to produce coordinated duet songs. Several functions have been attributed to gibbon songs, most of which emphasise a role in territorial advertisement, mate attraction and maintenance of pair and family bonds (Geissmann, 1999; Geissmann & Orgeldinger in press; Haimoff, 1984; Leighton, 1987).
The most prominent song contribution of female gibbons consists of a loud, stereotyped phrase, the great call. Depending on species, great calls typically comprise between 6-100 notes, have a duration of 6-30 s. The shape of individual great call notes and the intervals between the notes follow a species-specific pattern.
. A female song bout is usually introduced by a variable but simple series of notes termed the introductory sequence; it is produced only once in a song bout. Thereafter, great calls are produced with an interval of about 2 min. In the intervals, [are] so-called interlude sequences consisting of shorter, more variable phrases … The typical female song bout hence follows the sequential course ABCBCBCBC…,
As a rule, adult males do not produce great calls, but "male short phrases" only. Whereas female great calls remain essentially unchanged throughout a song bout, males gradually build up their phrases, beginning with single, simple notes. As less simple notes are introduced, these notes are combined to increasingly complex phrases, reaching the fully developed form only after several minutes of singing …
During duet songs, mated males and females combine their song contributions to produce complex, but relatively stereotyped vocal interactions… Both pair partners contribute to an introductory sequence at the beginning of the song bout (A). Thereafter, interlude sequences (B) and great call sequences (C) are produced in successive alternation…
During great call sequences the male becomes silent and does not resume calling until near or shortly after the end of the female's great call, when he will produce a coda.
Singing is rare in mammals. It occurs in members of 26 species in four primate genera: Indri, Tarsius, Callicebus, Hylobates. These are 11% of primate species and 4% of primate genera. Since the four singing genera are widely separated, they are thought to have evolved singing independently.
In all singing primates, both males and females sing, and duetting usually if not always occurs. All singing primates are monogamous (with the possible exception of humans).
Most bird species sing; often bird song is mostly male; duetting bird species are also usually monogamous.
In most mammalian species, sexual access is either determined by rank… and results in polygyny; or else … two individuals become “attached” to one another and then isolate themselves from other members of their species…
[In humans] what is common is… cooperative, mixed-sex social groups, with significant male care and provisioning of offspring, and relatively stable patterns of reproductive exclusion, mostly in the form of monogamous relationships.
Reproductive pairing is not found in exactly this pattern in any other species.
--Terence Deacon, “The Symbolic Species”
Some gibbons have developed a large “gular sac” apparently involved with breath control and/or resonance. Gular sac size and song complexity seem to correlate across species.
“the [siamang] duet is probably the most complicated opus sung by a land vertebrate other than man…”
--Marshall and Sugardjito (1986)
slowed x 4
(i.e. produce more offspring)
(i.e. produce more offspring grow or get borrowed)
and admires the ability of the Scythian nomads to win without
The Scythians indeed have in one respect, and that the very most important of all those that fall under man's control, shown themselves wiser than any nation upon the face of the earth. Their customs otherwise are not such as I admire. The one thing of which I speak is the contrivance whereby they make it impossible for the enemy who invades them to escape destruction, while they themselves are entirely out of his reach, unless it please them to engage with him. Having neither cities nor forts, and carrying their dwellings with them wherever they go; accustomed, moreover, one and all of them, to shoot from horseback; and living not by husbandry but on their cattle, their waggons the only houses that they possess, how can they fail of being unconquerable, and unassailable even?
sexual reproduction vs.imitation and borrowing
random mutation/recombination vs. explicit problem-solving
Origin: situation of captured thieves
If you analyze the options objectively, your best bet is to confess. But if everyone confesses, everyone is worse off than if everyone kept silent.
Generically: total cooperation is better than total non-cooperation; but any individual can then better his or her situation by “defecting”.
Temptation >> Reward >> Punishment >> Sucker’s payoff
[Also: (Temptation + Sucker)/2 <= Reward]
[A merchant] generally, indeed, neither intends to promote the public interest, nor knows how much he is promoting it. … [H]e intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention. … By pursuing his own interest he frequently promotes that of the society more effectually than when he really intends to promote it.
Wealth of Nations, Book IV