In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Evolution and the Theory of Games

ION, GENERAL CONCEPTIONS, SELF-CONSCIOUSNESS, MENTAL INDIVIDUALITY. It would be very difficult for any one with even much more knowledge than I possess, to determine how far animals exhibit any traces of these high mental powers. This difficulty arises from the impossibility of judging what passes through the mind of an animal; and again, the fact that writers differ to a great extent in the meaning which they attribute to the above terms, causes a further difficulty. If one may judge from various articles which have been published lately, the greatest stress seems to be laid on the supposed entire absence in animals of the power of abstraction, or of forming general concepts. But when a dog sees another dog at a distance, it is often clear that he perceives that it is a dog in the abstract; for when he gets nearer his whole manner suddenly changes, if the other dog be a friend. A recent writer remarks, that in all such cases it is a pure assumption to assert that the mental act is not essentially of the same nature in the animal as in man. If either refers what he perceives with his senses to a mental concept, then so do both. (44. Mr. Hookham, in a letter to Prof. Max Muller, in the 'Birmingham News,' May, 1873.) When I say to my terrier, in an eager voice (and I have made the trial many times), "Hi, hi, where is it?" she at once takes it as a sign that something is to be hunted, and generally first looks quickly all around, and then rushes into the nearest thicket, to scent for any game, but finding nothing, she looks up into any neighbouring tree for a squirrel. Now do not these actions clearly shew that she had in her mind a general idea or concept that some animal is to be discovered and hunted? It may be freely admitted that no animal is self-conscious, if by this term it is implied, that he reflects on such points, as whence he comes or whither he will go, or what is life and death, and so forth. But how can we feel sure that an old dog with an excellent memory and some power of imagination, as shewn by his dreams, never reflects on his past pleasures or pains in the chase? And this would be a form of self-consciousness. On the other hand, as Buchner (45. 'Conferences sur la Theorie Darwinienne,' French translat. 1869, p. 132.) has remarked, how little can the hardworked wife of a degraded Australian savage, who uses very few abstract words, and cannot count above four, exert her self-consciousness, or reflect on the nature of her own existence. It is generally admitted, that the higher animals possess memory, attention, association, and even some imagination and reason. If these powers, which differ much in different animals, are capable of improvement, there seems no great improbability in more complex faculties, such as the higher forms of abstraction, and selfconsciousness, etc., having been evolved through the development and combination of the simpler ones. It has been urged against the views here maintained that it is impossible to say at what point in the ascending scale animals become capable of abstraction, etc.; but who can say at what age this occurs in our young children? We see at least that such powers

https://www.jstage.jst.go.jp/article/ase1887/22/257/22_257_458/_pdf

The descent of man and selection in relation to sex

Seasonal changes in plasma glucocorticoid concentrations in free-living vertebrates.

Nothing in biology makes sense except in the light of evolution, quipped Theodosius Dobzhansky. The theory of evolution argues that each biological species was not suddenly and independently created but that all life forms are interrelated by virtue of having descended from common ancestors through the accumulation of modifications. Indeed, nothing we know about living organisms would make any sense if they were not so interrelated. And the theory that biological species are descended from common ancestors provides an indispensable heuristic to understand why living organisms are what they are and do what they do.

Nothing in Biology Makes Sense Except in the Light of Evolution

Maternal hormones as a tool to adjust offspring phenotype in avian species

Frogs of Boracéia

In the past decade, the academic community has increased considerably its activity concerning the teaching and learning of evolution. Despite such beneficial activity, the state of public understanding of evolution is considered woefully lacking by most researchers and educators. This lack of understanding affects evolution/science literacy, research, and academia in general. Not only does the general public lack an understanding of evolution but so does a considerable proportion of college graduates. However, it is not just evolutionary concepts that students do not retain. In general, college students retain little of what they supposedly have learned. Worse yet, it is not just students who have avoided science and math who fail to retain fundamental science concepts. Students who have had extensive secondary-level and college courses in science have similar deficits. We examine these issues and explore what distinguishes effective pedagogy from ineffective pedagogy in higher education in general and evolution education in particular. The fundamental problem of students' prior conceptions is considered and why prior conceptions often underpin students' misunderstanding of the evolutionary concepts being taught. These conceptions can often be discovered and addressed. We also attend to concerns about coverage of course content and the influence of religious beliefs, and provide helpful strategies to improve college-level teaching of evolution.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0014-3820.2002.tb00115.x

Perspective: teaching evolution in higher education

New data on the genders of young turtles from eggs incubated at controlled temperatures demonstrate temperature-dependent sex determination (TSD) in 17 species surveyed for the first time and corroborate TSD in another 11 species. The well-known pattern of males from cool temperatures and females from warm ones (=Pattern Ia) occurs in eight species and may occur in seven more. A pattern of cool females, intermediate males, and warm females (=Pattern II) occurs in ten species. Data on three species surveyed for the first time are compatible with genetic sex determination (GSD). Within Clemmys, C. guttata has TSD; C. insculpta, GSD. Comparisons among phylogenetic sister groups suggest at least four independent losses of TSD in turtles. Large variation in extent of sexual differentiation at hatching among TSD species vs GSD species obscures any evidence that either system provides earlier or more complete differentiation. Pattern Ia occurs mainly in species in which adult females average larger than adult males; Pattern II occurs mainly in species with females smaller than males or in which body size is not dimorphic. Among TSD reptiles generally, the smaller gender typically arises at the coolest incubation temperatures. The new data, together with a literature survey, invite four possible explanations for various aspects of sex determination in reptiles: phylogenetic inertia, temperature-dependent differential fitness, sib-avoidance, and group-structured adaptation in sex ratios. Key demographic features from the literature include a high incidence of unisexuality within clutches and a predominance of female biases in sex ratios of hatchlings but not in those of adults. Each of these explanations remains partly but not fully plausible. Explanations for the patterns of sex determination may ultimately require a combination of hypotheses.

Sex Determination in Turtles: Diverse Patterns and Some Possible Adaptive Values

Among reptiles that show temperature-dependent sex determination, sex ratios vary across constant incubation temperatures in ways sufficiently predictable to allow classifica- tion into patterns. One common pattern shows low temperatures yielding only males and high temperatures yielding only females. Another common pattern has low as well as high tempera- tures yielding only or mostly females and some intermediate temperatures yielding mostly males. Patterns tend to be associated with the direction of sexual dimorphism in adult size, especially for species with strong dimorphism. Pivotal temperatures (those yielding 1:l sex ratios) within the best-documented species and genera tend to increase with both latitude and longitude across central and southern North America. These geographic trends probably reflect factors that affect nest temperatures (duration of grow- ing season, insolation, and prevailing amounts of shading by vegetation). Data from a population of the alligator snapping turtle (Macroclemys temminckii) suggest that some embryos are temperature-independent females because these individuals become females even when they are shifted among male-producing temperatures during development. These indi- viduals are also more frequent in clutches of small eggs. In this and several other species, no constant incubation temperatures yield more than 75% males. 0 1994 WiIey-Liss, Inc.

/pdf/patterns-of-temperature-dependent-sex-determination-in-1ha2tlstgq.pdf

Patterns of temperature‐dependent sex determination in turtles

Most hypotheses that have been put forward in order to explain the persistence of environmental sex determination (ESD) in reptiles assume a relatively fixed association of sex with temperature-induced phenotype and no maternal influence on offspring sex. Here we demonstrate the association of maternally derived yolk hormone levels with the offspring sex ratio and describe two new aspects of temperature-dependent sex determination (TSD), i.e. seasonal variation in both thermal response and yolk steroid levels. Eggs from painted turtles (Chrysemys picta) were incubated at 28 degrees C. The hatchling sex ratio at 28 degrees C (i.e. the phenotypic reaction norm for sex at 28 degrees C) shifted seasonally from ca. 72% male to ca. 76% female. Yolk oestradiol (E2) increased seasonally while testosterone (T) decreased. The proportion of males in a clutch decreased as E2 levels increased and the E2:T ratio increased. These new findings are discussed in relation to heritability and adaptive explanations for the persistence of ESD in reptiles. Maternally derived yolk hormones may provide a mechanism for the seasonal shift in the sex ratio which in turn may help explain the persistence of ESD in reptiles. They may also explain those clutches of other reptiles with TSD that fail to yield only males at maximally masculinizing conditions.

/pdf/environmental-sex-determination-in-a-reptile-varies-360gg892ot.pdf

Craig E. Nelson

Papers

Frogs of Boracéia

Perspective: teaching evolution in higher education

Sex Determination in Turtles: Diverse Patterns and Some Possible Adaptive Values

Patterns of temperature‐dependent sex determination in turtles

Environmental sex determination in a reptile varies seasonally and with yolk hormones.