Longevity is associated with relative brain size in birds

Abstract

Brain size of vertebrates has long been recognized to evolve in close association with basic life‐history traits, including lifespan. According to the cognitive buffer hypothesis, large brains facilitate the construction of behavioral responses against novel socioecological challenges through general cognitive processes, which should reduce mortality and increase lifespan. While the occurrence of brain size–lifespan correlation has been well documented in mammals, much less evidence exists for a robust link between brain size and longevity in birds. The aim of this study was to use phylogenetically controlled comparative approach to test for the relationship between brain size and longevity among 384 avian species from 23 orders. We used maximum lifespan and maximum reproductive lifespan as the measures of longevity and accounted for a set of possible confounding effects, such as allometry, sampling effort, geographic patterns, and life‐history components (clutch size, incubation length, and mode of development). We found that both measures of longevity positively correlated with relative (residual) brain size. We also showed that major diversification of brain size preceded diversification of longevity in avian evolution. In contrast to previous findings, the effect of brain size on longevity was consistent across lineages with different development patterns, although the relatively low strength of this correlation could likely be attributed to the ubiquity of allomaternal care associated with the altricial mode of development. Our study indicates that the positive relationship between brain size and longevity in birds may be more general than previously thought.

Large-brained frogs mature later and live longer

“…We found a positive association between life span and relative brain size after controlling for several potential confounding ecological factors and phylogenetic nonindependence, which is congruent with what has previously been shown in mammals (Allman et al. ) and birds (Minias and Podlaszczuk ). Our results suggest that evolving a larger brain increases the age at maturation and so facilitates the evolution of a longer life span.…”

“…). Thus, via this mechanism, animals with larger brains may be expected to live longer (Hofman ; Minias and Podlaszczuk ); and this is what we found. Our data may especially be in line with such reasoning as the size of the ventral brain area was positively associated with longevity.…”

“…), including indicators of parental investment such as egg volume, total sperm length, and testes mass (). Also, longevity can be affected by geography (Minias and Podlaszczuk ). For instance, latitude is a strong predictor for life span in birds (Møller ).…”

“…Covariation of life-history traits is common across species (Harvey and Clutton-Brock 1985;Promislow and Harvey 1990;Bielby et al 2007), we therefore extracted information on life-history traits that are typically correlated with life span from our own previous studies (Fei et al 2010;Liao et al 2013;Liao et al 2018), including indicators of parental investment such as egg volume, total sperm length, and testes mass (Table S1). Also, longevity can be affected by geography (Minias and Podlaszczuk 2017). For instance, latitude is a strong predictor for life span in birds (Møller 2007).…”

Larger brains spur species diversification in birds

“…Birds represent an ideal system for investigating this question because they contain some of the species with the largest brains of all vertebrates, and the evolution of enlarged brains has independently occurred in different lineages (Lefebvre et al 2004). Avian species with larger brains, relative to their body size, have been found to experience lower mortality and live longer than species with smaller brains (Sol et al 2007;Minias and Podlaszczuk 2017), and are also more successful at coping with the challenges presented by new, altered, and varying environments (Sol et al 2005a;Sayol et al 2016b;Fristoe et al 2017). The "cognitive buffer" provided by enlarged brains is also supported by ample evidence.…”