For atheists. which life is more valuable ? a Human life or an animal's life?

Question:

For atheists. which life is more valuable ? a Human life or an animal's life?

Considering that atheists don't believe in God and thus they don't believe in a soul, it is just natural to think that to them a dog or a cat and elephant or a cow's life is just as valuable as a human life. Or is it not? If not, what makes it different?

Additional Details

1 week ago
I do acknowledge that: 1) human are "animals" according to science and 2)other religions believe animals have souls.

Just want to hear the best reasoned argument, one way or the other

Best Answer - Chosen by Asker: 1 week ago
I do acknowledge that: 1) human are "animals" according to science and 2)other religions believe animals have souls.

Just want to hear the best reasoned argument, one way or the other