Tinkering with pre-existing genes has long been known as a major way to create 
new genes. Recently, however, motherless protein-coding genes have been found to 
have emerged de novo from ancestral non-coding DNAs. How these genes originated 
is not well addressed to date. Here we identified 24 hominoid-specific de novo 
protein-coding genes with precise origination timing in vertebrate phylogeny. 
Strand-specific RNA-Seq analyses were performed in five rhesus macaque tissues 
(liver, prefrontal cortex, skeletal muscle, adipose, and testis), which were 
then integrated with public transcriptome data from human, chimpanzee, and 
rhesus macaque. On the basis of comparing the RNA expression profiles in the 
three species, we found that most of the hominoid-specific de novo 
protein-coding genes encoded polyadenylated non-coding RNAs in rhesus macaque or 
chimpanzee with a similar transcript structure and correlated tissue expression 
profile. According to the rule of parsimony, the majority of these 
hominoid-specific de novo protein-coding genes appear to have acquired a 
regulated transcript structure and expression profile before acquiring coding 
potential. Interestingly, although the expression profile was largely 
correlated, the coding genes in human often showed higher transcriptional 
abundance than their non-coding counterparts in rhesus macaque. The major 
findings we report in this manuscript are robust and insensitive to the 
parameters used in the identification and analysis of de novo genes. Our results 
suggest that at least a portion of long non-coding RNAs, especially those with 
active and regulated transcription, may serve as a birth pool for protein-coding 
genes, which are then further optimized at the transcriptional level.