Early life experience primes resistance to oxidative stress.

The extent to which early stress exposure is detrimental to darwinian fitness may depend on its severity, with mild stress exposure actually having a stimulatory and, possibly, beneficial effect through a hormetic response to the stressful stimulus. We need to understand such hormetic processes to determine how the early environment can help shape a phenotype adapted to the conditions the organism is most likely to experience in its adult environment. Using the zebra finch (Taeniopygia guttata), we tested the hypothesis that individuals exposed to mild heat stress earlier in life will suffer less oxidative stress when faced with high heat stress in adulthood than will individuals either not pre-exposed to heat stress or exposed to high heat stress earlier in life. Our findings demonstrate that early life exposure to mild heat stress primes the system to better withstand oxidative stress when encountering heat stress as an adult. These findings point to a potential mechanism linking early life experiences to future darwinian fitness.