The Evolutionary Puzzle

At first glance, it might seem counterintuitive for worker bees to give up their own chance to reproduce. After all, natural selection typically favors individuals that maximize their own reproductive success. So why do worker bees dedicate their lives to supporting the queen?

Kin Selection: The Evolutionary Explanation

This behavior is best explained by kin selection. Kin selection is a form of natural selection that favors behaviors increasing the reproductive success of relatives, even at a cost to the individual’s own reproduction. The key idea is that helping close kin can still promote the spread of an individual’s genes, because relatives share a significant proportion of their genetic material.

How It Works in Honey Bees

• Worker bees are daughters of the queen and share, on average, 75% of their genes with their full sisters due to the unique genetics of haplodiploid sex determination in bees.

• By helping the queen produce more sisters (future queens and workers), a worker bee passes on more of her own genes than she would by reproducing herself.

• This high relatedness makes altruistic behavior—such as feeding larvae, defending the hive, and tending to the queen—evolutionarily advantageous for workers.

Scientific Support

Research has shown that worker bee altruism is a textbook example of kin selection. Studies confirm that the degree of relatedness within colonies shapes the evolution of worker behaviors, including their willingness to help the queen and police each other’s reproduction. When relatedness is high, kin selection strongly favors altruism; when it is lower, competition and reproductive conflict can arise.

Other Theories and Why They Don’t Apply

• Group selection suggests traits evolve for the good of the group, but it lacks the genetic mechanism that kin selection provides.

• Sexual selection is about mate choice and competition for mates, not altruism among relatives.

• Natural selection is the overarching process, but kin selection is the specific mechanism explaining this behavior in bees.

Conclusion

Worker bees helping the queen reproduce is a classic example of kin selection. This evolutionary strategy explains why self-sacrificing behaviors can evolve in social insects, ensuring the survival and success of the hive’s shared genes.

Correct answer: (1) kin selection