Early Growth Reveals Relationships
Aligned to MS-LS4-3 — Next Generation Science Standards.
What this lesson teaches
Comparing pictures of how different species develop as embryos shows striking similarities in their early stages. The more alike their embryos look, the more closely related the species tend to be — another line of evidence for shared ancestry.
Worked example
In early embryo images, a fish, a chicken, and a human all show a tail and small arch structures near the head; these shared features in early development suggest the three species descend from a distant common ancestor.
Practice questions
- Look at side-by-side embryo drawings of several animals and circle features they share.
- Make a chart ranking which pairs of embryos look most alike.
- Explain, using the pictures, why similar early development is evidence that species are related.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
El desarrollo temprano revela parentescos
Comparar imágenes de cómo se desarrollan distintas especies como embriones muestra semejanzas notables en sus etapas tempranas. Cuanto más parecidos se ven sus embriones, más emparentadas suelen estar las especies — otra línea de evidencia de un ancestro común.
Ejemplo: En imágenes de embriones tempranos, un pez, un pollo y un ser humano muestran todos una cola y pequeñas estructuras en forma de arco cerca de la cabeza; estos rasgos compartidos en el desarrollo temprano sugieren que las tres especies descienden de un ancestro común lejano.
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