Behavioral Epiphenomena Revisited: Reply to Skok and Škorjanc

Abstract

In a recent article in this journal, Ethology, 2014 present arguments as to why fighting in piglets during suckling may not be an epiphenomenon as we had previously suggested Ethology, 119, 2013, 353 and provide several alternative explanations. Although the new information Skok and Škorjanc bring to this debate is carefully considered and important, I argue here that it is not sufficient to counter our original claim that fighting among piglets (and kittens) during suckling may be an epiphenomenon, a largely inconsequential by‐product, of developmental processes anticipating the use of these behaviors and associated anatomical structures in later functional contexts. However, the points Skok and Škorjanc raise contribute importantly to identifying areas where further information and experimental work are needed to resolve this and related behavioral issues. I therefore conclude that this debate, independent of any particular final outcome, constructively points to the general difficulty and need for caution in interpreting behavior in seemingly ‘obvious’ functional terms, and particularly during development.

Pattern of nipple use by puppies: A comparison of the dingo (Canis dingo) and the domestic dog (Canis familiaris).

“…For some years we have been studying mother–offspring interactions in the domestic cat ( Felis silvestris catus ) and domestic dog ( Canis familiaris ). Consistent with other reports in the literature (domestic cat: Ewer, 1960; Rosenblatt, 1971; puma, Puma concolor : Pfeifer, 1980; snow leopard, Panthera uncia : McVittie, 1978; Eurasian lynx, Lynx lynx : Glukhova & Naidenko, 2014), we have found that newborn kittens rapidly develop a clear order in the individual use of particular nipples, which they vigorously defend against encroaching littermates (Hudson, Raihani, González, Bautista, & Distel, 2009; Hudson & Distel, 2013; Hudson, 2014; Raihani, González, Arteaga, & Hudson, 2009). In contrast, and also in accord with a previous report (Rheingold, 1963), we have also found that puppies of the domestic dog do not do this, and that their pattern of suckling differs in several respects to the cat.…”

“…As obligate carnivores, usually lone hunters (Bradshaw, 2006; Fitzgerald & Turner, 2000; Sunquist & Sunquist, 2002), and dependent on their agility and climbing ability to escape danger, it should be advantageous for feline mothers to maintain a minimum number of active, burdensome mammary glands. This implies, however, that the kittens or cubs should ensure an adequate milk supply by regularly sucking their “own” nipple, thereby preventing its involution (Ewer, 1960; Hudson, own observations, Kim, Easter, & Hurley, 2001 in pigs, Sus scrofa ; see Hudson & Distel, 2013; Hudson, 2014 for reviews of the possible functional significance of the teat order in kittens and piglets). By contrast, more omnivorous and group- or pair-living canid mothers may have been under less selection pressure to minimize the number of active mammary glands.…”

The piglet case: commensalism as a distinct category of intraspecific animal relationships

“…Indeed, in the case of suckling behaviour by piglets, cooperation and competition are not distinct categories, because competition is interspersed with cooperation, and vice versa, which forms part of the comprehensive discussion on fighting during suckling (Hudson & Distel 2013;Skok & Škorjanc 2014;Hudson 2014). Therefore, the introduction of commensalism as an additional category in the classification of intraspecific relationships among animals might mitigate ambiguity, as this or similar behaviour probably also occurs in other species.…”