Why are the common strokes of these two characters written in different order?


Consider the following characters, 牛 and 生. I know both are not exactly
identical for sure.

According to the textbook I am using, the stroke orders are given as follows:

![enter image description here](https://i.stack.imgur.com/Mxcwi.png)

My question is why the third and fourth steps are different?




If you compare these two links:

<http://www.vividict.com/WordInfo.aspx?id=2831> for 牛 and
<http://www.vividict.com/WordInfo.aspx?id=2512> for 生

you can see how these characters have evolved over time.

Basically, 牛 starts as the image of the face of a water cow with its horns. so
the down stroke came last. Conversely, the life image emerged from 屮 and 土 at
one point during its evolution so you write the parts that come from the top
half first which means you wind up doing the down stroke as stroke 3 and then
two horizontal strokes after that.

Sometimes these historical artifacts of how to write it are better preserved
in Japanese than Chinese (esp. compared to mainland China).

