cannot use column references in default expression? - Mailing list pgsql-general

Could anyone please help me to get rid of following error? I want to set the 'ishuman' column based on the value of 'ID' column but it is not allowing me to do so. Any alternatives?

techdb=> CREATE TABLE Users (
       ID INTEGER,
       isHuman        BOOLEAN NOT NULL
                      DEFAULT (ID IS NULL)
                      CHECK (isHuman = ID IS NULL),
       Name  VARCHAR NOT NULL);
ERROR:  cannot use column references in default expression
techdb=>

Thanks,
Jignesh