kelly@bruno
Evolutionary Mysteries
The photo was taken over spring break of my boxer Ghost (who loves the beach). Among species, body size is a huge indicator of long life span. Typically, as size increases, life span increases. An interesting exception exists within species. The cost of larger size is especially evident in dog breeds. While the average poodle can live until 15, most Great Danes have a life span of only 6-8 years. Perhaps, artificial selection plays a large role in this as selective breeding of dogs, "has led to breeds that vary in body size by almost two orders of magnitude and in average life expectancy by a factor of two". While it is still mostly a mystery exactly why larger dogs have shorter life spans, many theories exists. Studies have shown that there is an increased baseline hazard for larger breeds; however, the true culprit is quicker aging. It appears that within species, a trade-off for larger size is an increased rate of aging.
Kraus, Cornelia, et al. “The Size–Life Span Trade-Off Decomposed: Why Large Dogs Die Young.” The American Naturalist, vol. 181, no. 4, 2013, pp. 492–505., www.jstor.org/stable/10.1086/669665.
Evolutionary Mysteries
The photo was taken over spring break of my boxer Ghost (who loves the beach). Among species, body size is a huge indicator of long life span. Typically, as size increases, life span increases. An interesting exception exists within species. The cost of larger size is especially evident in dog breeds. While the average poodle can live until 15, most Great Danes have a life span of only 6-8 years. Perhaps, artificial selection plays a large role in this as selective breeding of dogs, "has led to breeds that vary in body size by almost two orders of magnitude and in average life expectancy by a factor of two". While it is still mostly a mystery exactly why larger dogs have shorter life spans, many theories exists. Studies have shown that there is an increased baseline hazard for larger breeds; however, the true culprit is quicker aging. It appears that within species, a trade-off for larger size is an increased rate of aging.
Kraus, Cornelia, et al. “The Size–Life Span Trade-Off Decomposed: Why Large Dogs Die Young.” The American Naturalist, vol. 181, no. 4, 2013, pp. 492–505., www.jstor.org/stable/10.1086/669665.