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Why is it that when similar species mate they produce infertile offspring?

Mark Sterling
Mark Sterling
Research Editor · Jan 17, 2026 · Updated Apr 13, 2026

The number of chromosomes in a horse and donkey are different, and when they combine the mule has an odd number (63, rather than 62 or 64). This means the chromosomes can't match up into pairs so the mule is infertile.

38
Words

1 min
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#382
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The Short Answer

The number of chromosomes in a horse and donkey are different, and when they combine the mule has an odd number (63, rather than 62 or 64). This means the chromosomes can't match up into pairs so the mule is infertile.

Analysis

Key Concepts: Number, chromosomes, mule

This explanation focuses on number, chromosomes, mule and spans 38 words across 2 sentences. At 47% below the average Biology explanation (72 words), the answer takes a direct, no-frills approach — sometimes the simplest explanation is the most effective.

What This Answer Covers

This is a focused, single-point answer that gets directly to the core of the question without detours.

How This Compares in Biology

Ranked #382 of 500 Biology questions by answer depth (top 77%). This is a brief primer — the answer is intentionally short. For questions with a single core mechanism, brevity can actually be a strength.

Frequently Asked Questions

Is there a simple explanation for why it that when similar species mate they produce infertile offspring?

The number of chromosomes in a horse and donkey are different, and when they combine the mule has an odd number (63, rather than 62 or 64). This means the chromosomes can't match up into pairs so the mule is infertile.

How detailed is this explanation compared to similar Biology questions?

This is a brief answer at 38 words, ranked #382 of 500 Biology questions by depth. The key concepts covered are number, chromosomes, mule.

What approach does this answer take to explain it that when similar species mate they produce infertile off?

The explanation uses direct explanation across 38 words. It is categorized under Biology and addresses the question through 1 analytical lens.