title: Paternal and grandpaternal ages at conception and descendant telomere lengths in chimpanzees and humans.
abstract: Telomeres are repeating DNA at chromosome ends. Telomere length (TL) declines with age in most human tissues, and shorter TL is thought to accelerate senescence. In contrast, older men have sperm with longer TL; correspondingly, older paternal age at conception (PAC) predicts longer TL in offspring. This PAC-effect could be a unique form of transgenerational genetic plasticity that modifies somatic maintenance in response to cues of recent ancestral experience. The PAC-effect has not been examined in any non-human mammals.
  
  
  OBJECTIVE
  Here, we examine the PAC-effect in chimpanzees (Pan troglodytes). The PAC-effect on TL is thought to be driven by continual production of sperm-the same process that drives increased de novo mutations with PAC. As chimpanzees have both greater sperm production and greater sperm mutation rates with PAC than humans, we predict that the PAC-effect on TL will be more pronounced in chimpanzees. Additionally we examine whether PAC predicts TL of grandchildren.
  
  
  METHODS
  TL were measured using qPCR from DNA from blood samples from 40 captive chimpanzees and 144 humans.
  
  
  RESULTS
  Analyses showed increasing TL with PAC in chimpanzees (p = .009) with a slope six times that in humans (p = .026). No associations between TL and grandpaternal ages were found in humans or chimpanzees-although statistical power was low.
  
  
  CONCLUSIONS
  These results suggest that sperm production rates across species may be a determinant of the PAC-effect on offspring TL. This raises the possibility that sperm production rates within species may influence the TL passed on to offspring.
authors.affiliation: Department of Anthropology, University of Washington, Seattle, Washington.|Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington.
authors.forename: Dan T A
authors.initials: DT
authors.lastname: Eisenberg
authors.affiliation: Department of Anthropology, University of Utah, Salt Lake City, Utah.
authors.forename: Justin
authors.initials: J
authors.lastname: Tackney
authors.affiliation: Department of Human Genetics, University of Utah, Salt Lake City, Utah.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Cawthon
authors.affiliation: Department of Anthropology, University of Utah, Salt Lake City, Utah.
authors.forename: Christina Theresa
authors.initials: CT
authors.lastname: Cloutier
authors.affiliation: Department of Anthropology, University of Utah, Salt Lake City, Utah.
authors.forename: Kristen
authors.initials: K
authors.lastname: Hawkes
mesh_terms: D000328:Adult; D000818:Animals; D000885:Anthropology, Physical; D005075:Biological Evolution; D057890:Epigenomics; D006801:Humans; D016014:Linear Models; D008297:Male; D002679:Pan troglodytes / Q000235:genetics*; D010331:Paternal Age; D016615:Telomere / Q000737:chemistry* / Q000235:genetics*; D055815:Young Adult
keywords: adaptive intergenerational plasticity; aging; epigenetics; evolution; life history