gene expression that is further passed down to their offspring, allowing for them also to better thrive in their environment. The classic case study of the rats who experience licking and grooming from their mothers pass this trait to their offspring shows that a mutation in the DNA sequence is not required for a heritable change Basically, a high degree of maternal nurturing makes the offspring of that mother more likely to nurture their own children with a high degree of care as well. Rats with a lower degree of maternal nurturing are less likely to nurture their own offspring with so much care. Also, rates of epigenetic mutations, such as DNA methylation, are much higher than rates of mutations transmitted genetically and are easily reversed. This provides a way for variation within a species to rapidly increase, in times of stress, providing opportunity for adaptation to newly arising selection pressures. Lamarckism Lamarckism supposes that species acquire characteristics to deal with challenges experienced during their lifetimes, and that such accumulations are then passed to their offspring. In modern terms, this transmission from parent to offspring could be considered a method of epigenetic inheritance. Scientists are now questioning the framework of the modern synthesis, as epigenetics to some extent is Lamarckist rather than Darwinian. While some evolutionary biologists have dismissed epigenetics' impact on evolution entirely, others are exploring a fusion of epigenetic and traditional genetic inheritance. See also Transgenerational epigenetic inheritance References Epigenetics Evolutionary biology