Yin and Yang symbols could be the earliest of abstract written language. 

Yin and Yang are the basic expression of the Ancient Chinese. It is equivalent to a bit in today's binary language. Each Yao (bit) represents either Yin (0), female force of nature, or Yang (1), male force of nature. Yin (0), female, , is two short little hyphens with a gap in between. Yang, male, , is one continuous hyphen-like line.
If you are graphic oriented, you can use some graphic imagination to help you remember the female and male symbols. You might also be happy to know that certain historians believe the ancient human being noticed the first difference between female (Yin) and male (Yang) from the most direct and important areas of our body.
If you are a geek, you can fashionably call them "zero (Yin)" and "one (Yang)". You should know one important fact:  the Chinese character for number one, is exactly the same as the Yang (male) symbol
,one continuous hyphen like line. I do not know if all the historians will agree the ancient Chinese use the Yin (female) symbol to represents 'zero'.  It is definitely appropriate and academically accepted to call it zero today. When the ancient symbols were first put into computer, Yin (female) was represented by zero and one represented Yang (male).