Peter L. Hurd | |
---|---|
Alma mater | Carleton University, Simon Fraser University, Stockholm University |
Known for | finger length and digit ratio, social behaviour esp. in conflict |
Scientific career | |
Fields | biology, psychology |
Institutions | University of Texas, University of Alberta |
Peter L. Hurd is an academic specialising in biology. He is an Associate Professor aligned to the Department of Psychology's Biocognition Unit, and the University's Centre for Neuroscience at the University of Alberta. His research primarily focuses on the study of the evolution of aggressive behaviour, including investigation of aggression, communication and other social behaviour which takes place between animals with conflicting interests. Major tools for this research are mathematical modeling (principally game theory and genetic algorithms). He is also interested in how the process of sexual differentiation produces individual differences in social behaviour.
Hurd conducted a study on digit ratios suggesting a positive correlation in males between aggressive tendency and the ratio of the lengths of the ring finger to his index finger. These gathered significant media attention, being reported on the BBC, [1] in The New York Times , [2] Discover Magazine , [3] Scientific American Mind , [4] National Geographic [5] and on Jay Leno. [6]
Some of Hurd's most cited papers deal with the evolution of mating displays, specifically the idea that sexually selected traits have evolved to exploit previously existing biases in the sensory, or recognition, systems of their receivers, rather than being handicapped displays [7] [8] Hurd has argued against the handicap principle view of animal communication, demonstrating the evolutionary stability of conventional (non-handicap) threat displays using game theoretical models. [9] [10] [11] Adding empirical support to this theoretical work, Hurd has also argued that threat displays in birds, [12] and headbob displays in the lizard Anolis carolinensis [13] are conventional signals, rather than handicaps. Hurd attributes the preponderance of handicap models in biology to the use of simple signalling games which are incapable of modelling conventional signalling. [14]
Hurd has classified models of fighting behaviour into those driven by: 1) fighting ability (aka resource holding potential), 2) perceived value of winning, and 3) aggressiveness and argues that if variation in the last trait -aggressiveness- exists in a biologically meaningful way, it ought to be fixed for life at an early stage of development. [15] Many studies on both human, and non-human, animals suggest that inter-individual variation in adult aggressiveness is largely organised by prenatal exposure to androgens. Digit ratio (2D:4D, the ratio of index to ring finger length) is a widely used as a proxy measure for prenatal testosterone exposure. Hurd demonstrated that men with more feminine typical-digit ratios showed lower aggressive tendency than males with more masculine-typical digit ratios. [16]
Among his other research into digit ratio, Hurd has demonstrated that, while there is no difference in digit ratio between the sexes in most laboratory mice, that pups which gested[ spelling? ] next to brothers have higher digit ratios than those whose uterine neighbours were sisters, [17] [18] and that the large differences in digit ratios between populations may be explained by Allen's rule and Bergmann's rule. [19]
Strongly influenced as a youth by the anarcho-punk movement and such influences as Jonathan Kozol and A. S. Neill's Summerhill School, Hurd was an enthusiastic member of a student run free school group while unenthusiastically attending Colonel By Secondary School. [20] He then completed a BSc at Carleton University, Canada in 1990, followed by an MSc in 1993 from Simon Fraser University. He moved to Sweden to undertake a PhD at Stockholm University (Awarded in 1997) before committing to an initial postdoctoral fellowship with Mike Ryan at the University of Texas. Hurd then became a lecturer at the University of Texas in 2000 until 2001 when he moved to the University of Alberta, Canada as an Assistant Professor. Hurd was promoted to Associate Professor in 2007.
Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex. These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more attractive or prefer more attractive partners to produce offspring. Successful males benefit from frequent mating and monopolizing access to one or more fertile females. Females can maximise the return on the energy they invest in reproduction by selecting and mating with the best males.
Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual; although it can be channeled into creative and practical outlets for some. It may occur either reactively or without provocation. In humans, aggression can be caused by various triggers, from frustration due to blocked goals to feeling disrespected. Human aggression can be classified into direct and indirect aggression; whilst the former is characterized by physical or verbal behavior intended to cause harm to someone, the latter is characterized by behavior intended to harm the social relations of an individual or group.
The digit ratio is the ratio of the lengths of different digits or fingers on a hand, the study of which has been considered pseudoscience. The 2D:4D ratio is the most studied digit ratio and is calculated by dividing the length of the index finger of a given hand by the length of the ring finger of the same hand. Although studies have claimed to show a correlation between the 2D:4D digit ratio and various physical and behavioral traits, these studies have drawn criticism for irreproducible or contradictory findings, exaggerated claims of usefulness, and lack of high quality research protocols.
A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners with which to mate. A lek can also indicate an available plot of space able to be utilized by displaying males to defend their own share of territory for the breeding season. A lekking species is characterised by male displays, strong female mate choice, and the conferring of indirect benefits to males and reduced costs to females. Although most prevalent among birds such as black grouse, lekking is also found in a wide range of vertebrates including some bony fish, amphibians, reptiles, and mammals, and arthropods including crustaceans and insects.
Behavioral ecology, also spelled behavioural ecology, is the study of the evolutionary basis for animal behavior due to ecological pressures. Behavioral ecology emerged from ethology after Niko Tinbergen outlined four questions to address when studying animal behaviors: What are the proximate causes, ontogeny, survival value, and phylogeny of a behavior?
The handicap principle is a hypothesis proposed by the biologist Amotz Zahavi to explain how evolution may lead to "honest" or reliable signalling between animals which have an obvious motivation to bluff or deceive each other. It suggests that costly signals must be reliable signals, costing the signaller something that could not be afforded by an individual with less of a particular trait. For example, in sexual selection, the theory suggests that animals of greater biological fitness signal this status through handicapping behaviour, or morphology that effectively lowers this quality. The central idea is that sexually selected traits function like conspicuous consumption, signalling the ability to afford to squander a resource. Receivers then know that the signal indicates quality, because inferior-quality signallers are unable to produce such wastefully extravagant signals.
The game of chicken, also known as the hawk–dove game or snowdrift game, is a model of conflict for two players in game theory. The principle of the game is that while the ideal outcome is for one player to yield, the individuals try to avoid it out of pride for not wanting to look like a "chicken". Each player taunts the other to increase the risk of shame in yielding. However, when one player yields, the conflict is avoided, and the game is for the most part over.
Evolutionary game theory (EGT) is the application of game theory to evolving populations in biology. It defines a framework of contests, strategies, and analytics into which Darwinian competition can be modelled. It originated in 1973 with John Maynard Smith and George R. Price's formalisation of contests, analysed as strategies, and the mathematical criteria that can be used to predict the results of competing strategies.
Dog aggression expressed by dogs is considered to be normal behaviour and various types of aggression are influenced by a dog's environment and genetic predisposition. Dogs commonly display possessive aggression when defending resources or themselves.
Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals, both within species and across species. The central question is when organisms with conflicting interests, such as in sexual selection, should be expected to provide honest signals rather than cheating. Mathematical models describe how signalling can contribute to an evolutionarily stable strategy.
In biology, altruism refers to behaviour by an individual that increases the fitness of another individual while decreasing the fitness of themselves. Altruism in this sense is different from the philosophical concept of altruism, in which an action would only be called "altruistic" if it was done with the conscious intention of helping another. In the behavioural sense, there is no such requirement. As such, it is not evaluated in moral terms—it is the consequences of an action for reproductive fitness that determine whether the action is considered altruistic, not the intentions, if any, with which the action is performed.
In animal communication, an alarm signal is an antipredator adaptation in the form of signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predators. For example, the alarm call of the blackbird is a familiar sound in many gardens. Other animals, like fish and insects, may use non-auditory signals, such as chemical messages. Visual signs such as the white tail flashes of many deer have been suggested as alarm signals; they are less likely to be received by conspecifics, so have tended to be treated as a signal to the predator instead.
In biology, resource holding potential (RHP) is the ability of an animal to win an all-out fight if one were to take place. The term was coined by Geoff Parker to disambiguate physical fighting ability from the motivation to persevere in a fight. Originally the term used was 'resource holding power', but 'resource holding potential' has come to be preferred. The latter emphasis on 'potential' serves as a reminder that the individual with greater RHP does not always prevail.
Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce. By contrast, interspecific competition occurs when members of different species compete for a shared resource. Members of the same species have rather similar requirements for resources, whereas different species have a smaller contested resource overlap, resulting in intraspecific competition generally being a stronger force than interspecific competition.
In evolution, cooperation is the process where groups of organisms work or act together for common or mutual benefits. It is commonly defined as any adaptation that has evolved, at least in part, to increase the reproductive success of the actor's social partners. For example, territorial choruses by male lions discourage intruders and are likely to benefit all contributors.
Growling is a low, guttural vocalization produced by animals as an aggressive warning but can also be found in other contexts such as playful behaviors or mating. Different animals will use growling in specific contexts as a form of communication. In humans, low or dull rumbling noises may also be emitted when they are discontent with something or they are angry, although this human sound is often termed "groaning".
Sexual cannibalism is when an animal, usually the female, cannibalizes its mate prior to, during, or after copulation. It is a trait observed in many arachnid orders and several insect orders. Several hypotheses to explain this seemingly paradoxical behavior have been proposed. The adaptive foraging hypothesis, aggressive spillover hypothesis and mistaken identity hypothesis are among the proposed hypotheses to explain how sexual cannibalism evolved. This behavior is believed to have evolved as a manifestation of sexual conflict, occurring when the reproductive interests of males and females differ. In many species that exhibit sexual cannibalism, the female consumes the male upon detection. Females of cannibalistic species are generally hostile and unwilling to mate; thus many males of these species have developed adaptive behaviors to counteract female aggression.
Agonistic behaviour is any social behaviour related to fighting. The term has broader meaning than aggressive behaviour because it includes threats, displays, retreats, placation, and conciliation. The term "agonistic behaviour" was first implemented by J.P Scott and Emil Fredericson in 1951 in their paper "The Causes of Fighting in Mice and Rats" in Physiological Zoology.Agonistic behaviour is seen in many animal species because resources including food, shelter, and mates are often limited.
A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ("dances"), vocalizations, mechanical sound production, or displays of beauty, strength, or agonistic ability.
Human mate guarding refers to behaviours employed by both males and females with the aim of maintaining reproductive opportunities and sexual access to a mate. It involves discouraging the current mate from abandoning the relationship whilst also warding off intrasexual rivals. It has been observed in many non-human animals, as well as humans. Sexual jealousy is a prime example of mate guarding behaviour. Both males and females use different strategies to retain a mate and there is evidence that suggests resistance to mate guarding also exists.