Male deer with better sperm invest in male offspring.

The fertility of male red deer helps to determine the sex of their offspring, say biologists in Spain. The best-quality sperm tends to father sons, while the less healthy sperm tends to lead to daughters.

Read the story here.

Male deer with better sperm invest in male offspring.

The fertility of male red deer helps to determine the sex of their offspring, say biologists in Spain. The best-quality sperm tends to father sons, while the less healthy sperm tends to lead to daughters.

Read the story here.