I found a way to style all previous sibling elements (as opposed to ~), depending on your needs.

Suppose you have a list of links, and when hovering over one of the links, all previous links should turn red. You can do this:

/* 默认链接颜色为蓝色 */
.parent a {
  color: blue;
}

/* 先前的兄弟元素应为红色 */
.parent:hover a {
  color: red;
}
.parent a:hover,
.parent a:hover ~ a {
  color: blue;
}

<div class="parent">
  <a href="#">链接</a>
  <a href="#">链接</a>
  <a href="#">链接</a>
  <a href="#">链接</a>
  <a href="#">链接</a>
</div>

No, there is no "previous sibling selector".

Relevantly, ~ is used for general successor sibling selectors (meaning the element is after this element, but not necessarily immediately after it), and is a CSS3 selector. is used for the next sibling selector, which is CSS2.1.

See Adjacent Sibling Selectors from Selectors Level 3 and ## from Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification #5.7 Adjacent sibling selector.