On Earth, the human practice of celebrating birthdays is an annual event marking the anniversary of a person's birth. It serves as a time for social gatherings and expressions of affection, where friends and family come together to commemorate the life of the individual. The cultural significance of birthdays lies in the recognition of the individual's existence and their accumulation of experience and wisdom over time. Humans often engage in rituals such as gift-giving, cake-cutting, and the singing of 'Happy Birthday.' These practices showcase the importance of interpersonal connections, shared experiences, and the passage of time in human culture.
You are an alien anthropologist studying Earth. Describe the human practice of celebrating birthdays and its significance in their culture.