Archive | April 2016

Cuckoldary is rare in humans!

Human behavioral scientists argue that extra-pair copulation is adaptive in human females, as through extra-pair copulation, women can acquire good genes from other potential mates. This is suggested because it is found that women experience greater sexual attraction to particular extra-pair men, but not their own partners, during their highest peak of fertility (Gangestad & Thornhil, 2008).

However, recent genetic evidences cast doubt on such arguments and suggest that the rate of cuckoldry is very low in humans (around 1 percent). To achieve historical records on cuckoldry, scientists compare family specific Y chromosomal variation between men that based on genealogical evidence, are patrilineally related. “The surprising result of these new studies is that human extra-pair paternity rates have stayed near-constant at around 1% across several human societies over the past several hundred years” (Larmuseau et al., 2016). Greeff and Erasmus (2015) also showed that genetic analysis in Afrikaner families in South Africa shows 0.9% rate of cuckoldry and argued that given the current data on historical populations we have to conclude that, at least for Western human populations, cuckoldry rate is probably in the range of 1%”.

So what does it mean? Does the rarity of cuckoldry in human historical records mean that women do not look for potential mates with good genes, or it simply means that human men are good in mate retention and anti-cuckoldry tactics? That’s the question that should be considered now.

————————————————— Gangestad, S., & Thornhill, R. (2008). Human oestrus Proceedings of the Royal Society B: Biological Sciences, 275 (1638), 991-1000 DOI: 10.1098/rspb.2007.1425

Greeff, J., & Erasmus, J. (2015). Three hundred years of low non-paternity in a human population Heredity, 115 (5), 396-404 DOI: 10.1038/hdy.2015.36

Larmuseau MH, Matthijs K, & Wenseleers T (2016). Cuckolded Fathers Rare in Human Populations. Trends in ecology & evolution, 31 (5), 327-9 PMID: 27107336

Mate Retention Tactics Decline with Age of Men

Physical attractiveness influences mate selection across cultures, and youthfulness of women is associated with their future reproductive value and fertility. Men attribute importance to youthful features in females such as large eyes, small nose, higher pitched voice, and full lips and perceive these neotenous features as attractive. More feminine women report more frequently being guarded by their partners than less feminine and less attractive women; (Mate retention or mate guarding tactics are behaviors that men and women use to reduce the likelihood of their partner’s infidelity. For example, vigilance, monopolization of mate’s time, emotional manipulation, and derogation of competitors are just to name a few).

Additionally, men undergo hormonal (i.e. testosterone) age-related changes which are associated with decreased ability to attract mates, compete with rival men, decreased sexual motivation, energy availability, and a compromised ability to acquire resources. Men over 45 years report decreased sexual desire, sexual arousal, and activity.

In their recent paper, Pazhoohi, Jahromi, and Doyle (2016) showed that as men age, mate retention tactic use declines. Considering age-dependent testosterone decrease and the association of testosterone with the intensity of mate retention, they showed that men show a lesser degree of mate retention behaviors as they age.

However, one limitation of their study has been that they have not measured testosterone, as they state “The major limitation of the current study is the lack of direct measures of testosterone from male participants. Further investigations would be appropriate to test circulating or salivary testosterone levels and their relationship to mate retention behavior performed by men and at what age.”

ResearchBlogging.orgPazhoohi, F., Jahromi, A., & Doyle, J. (2016). Mate Retention Tactics Decline with Age of Iranian Men Evolutionary Psychological Science DOI: 10.1007/s40806-016-0046-8