WASHINGTON (AP) — The holiday season is a time for giving thanks, giving gifts — and for many, a time for giving back.Food banks, services that deliver meals to seniors and other U.S. charities typically see a surge in volunteering between Thanksgiving and the end of the year. But there are good reasons to volunteer at any time of the year.Alfred Del Grosso volunteers weekly to work the lunch shift at Shepherd’s Table, a food bank in Silver Spring, Maryland. “I feel more connected to the broader community,” he said.AdvertisementAdvertisementAdvertisementAdvertisementMost Thursdays, the retired chemist from Kensington, Maryland, also lends an unpaid hand to help clear fallen trees and brush from local trails with the Potomac Appalachian Trail Club. “It’s mostly volunteers who help maintain the trails,” he said.Researchers who study human evolution and social psychology say that giving back is deeply rooted in human nature. Volunteers say they feel closer ties to the communities they serve.“When we feel grateful for all we have, that motivates us to do good things for other people who have helped us, and also to do good things for new people,” said Sarah Schnitker, a psychologist at Baylor University.“There’s a nice upwards reciprocal spiral between gratitude and generosity,” often enhanced at holiday times, she said.AdvertisementAdvertisementAdvertisementAdvertisementFor many in the U.S., the season most associated with giving, receiving and volunteering runs from Thanksgiving through Hanukkah and Christmas to New Year’s.But around the world, a giving season or festival is present in many cultures, said Amrisha Vaish, a developmental psychologist at the University of Virginia.“Nearly all cultures have events or public festivals that allow people to express gratitude,” she said. “In Hinduism, Divali is a time of lights and festiveness and good eating, but also a time in which people give gifts to really express what people have meant to them.”For Muslims, Ramadan, which ends with the festival of Eid al-Fitr, is a time for reflection, gratitude and acts of charity. Many Buddhist traditions also emphasize gratitude.AdvertisementAdvertisementAdvertisementAdvertisementThe common purpose of such seasons, which also include non-religious acts of service, is to reinforce our natural cooperative tendencies, Vaish said.More in Lifestyle“In human evolutionary history over hundreds of thousands of years, we’ve had to become cooperative in order to work together and survive as a species,” she said.“We don’t have sharp c …